From 33f3eebcf07ad6e6ac0263a24142e7873878f70d Mon Sep 17 00:00:00 2001
From: Jake-Moss <jake.moss@uqconnect.edu.au>
Date: Mon, 16 Sep 2024 11:51:10 +1000
Subject: [PATCH 01/15] Add drop_gens, coerce_to_context, and
 infer_context_mapping functions

WIp

wip
---
 src/flint/flint_base/flint_base.pxd |   2 +
 src/flint/flint_base/flint_base.pyx | 157 ++++++++++++++++++++++++++--
 src/flint/flintlib/types/flint.pxd  |   2 +
 src/flint/types/fmpq_mpoly.pyx      |  19 ++++
 src/flint/types/fmpz_mod_mpoly.pyx  |  19 ++++
 src/flint/types/fmpz_mpoly.pyx      |  48 ++++-----
 src/flint/types/nmod_mpoly.pyx      |  19 ++++
 7 files changed, 230 insertions(+), 36 deletions(-)

diff --git a/src/flint/flint_base/flint_base.pxd b/src/flint/flint_base/flint_base.pxd
index daf22a96..99e50c23 100644
--- a/src/flint/flint_base/flint_base.pxd
+++ b/src/flint/flint_base/flint_base.pxd
@@ -1,4 +1,5 @@
 from flint.flintlib.types.mpoly cimport ordering_t
+from flint.flintlib.types.flint cimport slong
 
 cdef class flint_elem:
     pass
@@ -50,6 +51,7 @@ cdef class flint_mpoly(flint_elem):
     cdef _isub_mpoly_(self, other)
     cdef _imul_mpoly_(self, other)
 
+    cdef _compose_gens_(self, ctx, slong *mapping)
 
 cdef class flint_mat(flint_elem):
     pass
diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index cfe57fc9..68aa1c5f 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -2,6 +2,7 @@ from flint.flintlib.types.flint cimport (
     FLINT_BITS as _FLINT_BITS,
     FLINT_VERSION as _FLINT_VERSION,
     __FLINT_RELEASE as _FLINT_RELEASE,
+    slong,
 )
 from flint.utils.flint_exceptions import DomainError
 from flint.flintlib.types.mpoly cimport ordering_t
@@ -344,13 +345,20 @@ cdef class flint_mpoly_context(flint_elem):
         return tuple(self.gen(i) for i in range(self.nvars()))
 
     def variable_to_index(self, var: Union[int, str]) -> int:
-        """Convert a variable name string or possible index to its index in the context."""
+        """
+        Convert a variable name string or possible index to its index in the context.
+
+        If ``var`` is negative, return the index of the ``self.nvars() + var``
+        """
         if isinstance(var, str):
             try:
                 i = self.names().index(var)
             except ValueError:
                 raise ValueError("variable not in context")
         elif isinstance(var, int):
+            if var < 0:
+                var = self.nvars() + var
+
             if not 0 <= var < self.nvars():
                 raise IndexError("generator index out of range")
             i = var
@@ -379,7 +387,7 @@ cdef class flint_mpoly_context(flint_elem):
             names = (names,)
 
         for name in names:
-            if isinstance(name, str):
+            if isinstance(name, (str, bytes)):
                 res.append(name)
             else:
                 base, num = name
@@ -415,10 +423,14 @@ cdef class flint_mpoly_context(flint_elem):
         return ctx
 
     @classmethod
-    def from_context(cls, ctx: flint_mpoly_context):
+    def from_context(cls, ctx: flint_mpoly_context, names=None, ordering=None):
+        """
+        Get a new context from an existing one. Optionally override ``names`` or
+        ``ordering``.
+        """
         return cls.get(
-            ordering=ctx.ordering(),
-            names=ctx.names(),
+            names=ctx.names() if names is None else names,
+            ordering=ctx.ordering() if ordering is None else names,
         )
 
     def _any_as_scalar(self, other):
@@ -451,6 +463,47 @@ cdef class flint_mpoly_context(flint_elem):
             exp_vec = (0,) * self.nvars()
         return self.from_dict({tuple(exp_vec): coeff})
 
+    def drop_gens(self, *gens: str | int):
+        """
+        Get a context with the specified generators removed.
+
+            >>> from flint import fmpz_mpoly_ctx
+            >>> ctx = fmpz_mpoly_ctx.get(('x', 'y', 'z', 'a', 'b'))
+            >>> ctx.drop_gens('x', -2)
+            fmpz_mpoly_ctx(3, '<Ordering.lex: 'lex'>', ('y', 'z', 'b'))
+        """
+        nvars = self.nvars()
+        gen_idxs = set(self.variable_to_index(i) for i in gens)
+
+        if len(gens) > nvars:
+            raise ValueError(f"expected at most {nvars} unique generators, got {len(gens)}")
+
+        remaining_gens = []
+        for i in range(nvars):
+            if i not in gen_idxs:
+                remaining_gens.append(self.py_names[i])
+
+        return self.from_context(self, names=remaining_gens)
+
+    def infer_generator_mapping(self, ctx: flint_mpoly_context):
+        """
+        Infer a mapping of generator indexes from this contexts generators, to the
+        provided contexts generators. Inference is done based upon generator names.
+
+            >>> from flint import fmpz_mpoly_ctx
+            >>> ctx = fmpz_mpoly_ctx.get(('x', 'y', 'z', 'a', 'b'))
+            >>> ctx2 = fmpz_mpoly_ctx.get(('b', 'a'))
+            >>> ctx.infer_generator_mapping(ctx2)
+            {3: 1, 4: 0}
+        """
+        gens_to_idxs = {x: i for i, x in enumerate(self.names())}
+        other_gens_to_idxs = {x: i for i, x in enumerate(ctx.names())}
+        return {
+            gens_to_idxs[k]: other_gens_to_idxs[k]
+            for k in (gens_to_idxs.keys() & other_gens_to_idxs.keys())
+        }
+
+
 cdef class flint_mod_mpoly_context(flint_mpoly_context):
     @classmethod
     def _new_(_, flint_mod_mpoly_context self, names, prime_modulus):
@@ -472,11 +525,15 @@ cdef class flint_mod_mpoly_context(flint_mpoly_context):
         return *super().create_context_key(names, ordering), modulus
 
     @classmethod
-    def from_context(cls, ctx: flint_mod_mpoly_context):
+    def from_context(cls, ctx: flint_mod_mpoly_context, names=None, ordering=None, modulus=None):
+        """
+        Get a new context from an existing one. Optionally override ``names``,
+        ``modulus``, or ``ordering``.
+        """
         return cls.get(
-            names=ctx.names(),
-            modulus=ctx.modulus(),
-            ordering=ctx.ordering(),
+            names=ctx.names() if names is None else names,
+            modulus=ctx.modulus() if modulus is None else modulus,
+            ordering=ctx.ordering() if ordering is None else ordering,
         )
 
     def is_prime(self):
@@ -869,6 +926,88 @@ cdef class flint_mpoly(flint_elem):
         """
         return zip(self.monoms(), self.coeffs())
 
+    def drop_unused_gens(self):
+        """
+        Remove unused generators from this polynomial. Returns a potentially new
+        context, and potentially new polynomial.
+
+        A generator is unused if it's maximum degree is 0.
+
+            >>> from flint import fmpz_mpoly_ctx
+            >>> ctx = fmpz_mpoly_ctx.get(('x', 4))
+            >>> ctx2 = fmpz_mpoly_ctx.get(('x1', 'x2'))
+            >>> f = sum(ctx.gens()[1:3])
+            >>> f
+            x1 + x2
+            >>> new_ctx, new_f = f.drop_unused_gens()
+            >>> new_ctx
+            fmpz_mpoly_ctx(2, '<Ordering.lex: 'lex'>', ('x1', 'x2'))
+            >>> new_f
+            x1 + x2
+        """
+        new_ctx = self.context().drop_gens(
+            *(i for i, x in enumerate(self.degrees()) if not x)
+        )
+        return new_ctx, self.coerce_to_context(new_ctx)
+
+    def coerce_to_context(self, ctx, mapping: dict[str | int, str | int] = None):
+        """
+        Coerce this polynomial to a different context.
+
+        This is equivalent to composing this polynomial with the generators of another
+        context. By default the mapping between contexts is inferred based on the name
+        of the generators. Generators with names that are not found within the other
+        context are mapped to 0. The mapping can be explicitly provided.
+
+        The resulting polynomial is also normalised.
+
+            >>> from flint import fmpz_mpoly_ctx
+            >>> ctx = fmpz_mpoly_ctx.get(('x', 'y', 'a', 'b'))
+            >>> ctx2 = fmpz_mpoly_ctx.get(('a', 'b'))
+            >>> x, y, a, b = ctx.gens()
+            >>> f = x + 2*y + 3*a + 4*b
+            >>> f.coerce_to_context(ctx2)
+            3*a + 4*b
+            >>> f.coerce_to_context(ctx2, mapping={"x": "a", "b": 0})
+            5*a
+        """
+        cdef:
+            slong *c_mapping
+            slong i
+
+        if not typecheck(ctx, type(self.ctx)):
+            raise ValueError(
+                f"provided context is not a {self.ctx.__class__.__name__}"
+            )
+        elif self.ctx is ctx:
+            return self
+
+        if mapping is None:
+            mapping = self.ctx.infer_generator_mapping(ctx)
+        else:
+            mapping = {
+                self.ctx.variable_to_index(k): ctx.variable_to_index(v)
+                for k, v in mapping.items()
+            }
+
+        try:
+            c_mapping = <slong *> libc.stdlib.malloc(self.ctx.nvars() * sizeof(slong *))
+            if c_mapping is NULL:
+                raise MemoryError("malloc returned a null pointer")
+
+            for i in range(self.ctx.nvars()):
+                c_mapping[i] = <slong>-1
+
+            for k, v in mapping.items():
+                c_mapping[k] = <slong>v
+
+            return self._compose_gens_(ctx, c_mapping)
+        finally:
+            libc.stdlib.free(c_mapping)
+
+    cdef _compose_gens_(self, ctx, slong *mapping):
+        raise NotImplementedError("abstract method")
+
 
 cdef class flint_series(flint_elem):
     """
diff --git a/src/flint/flintlib/types/flint.pxd b/src/flint/flintlib/types/flint.pxd
index 8db56127..120bf1da 100644
--- a/src/flint/flintlib/types/flint.pxd
+++ b/src/flint/flintlib/types/flint.pxd
@@ -59,8 +59,10 @@ cdef extern from *:
 cdef extern from "flint/flint.h":
     """
     #define SIZEOF_ULONG sizeof(ulong)
+    #define SIZEOF_SLONG sizeof(slong)
     """
     int SIZEOF_ULONG
+    int SIZEOF_SLONG
     const char * FLINT_VERSION
     const int __FLINT_RELEASE
     const int FLINT_BITS
diff --git a/src/flint/types/fmpq_mpoly.pyx b/src/flint/types/fmpq_mpoly.pyx
index 0e86a3c8..80ec0009 100644
--- a/src/flint/types/fmpq_mpoly.pyx
+++ b/src/flint/types/fmpq_mpoly.pyx
@@ -20,7 +20,9 @@ from flint.flintlib.functions.fmpq_mpoly cimport (
     fmpq_mpoly_add,
     fmpq_mpoly_add_fmpq,
     fmpq_mpoly_clear,
+    fmpq_mpoly_combine_like_terms,
     fmpq_mpoly_compose_fmpq_mpoly,
+    fmpq_mpoly_compose_fmpq_mpoly_gen,
     fmpq_mpoly_ctx_init,
     fmpq_mpoly_degrees_fmpz,
     fmpq_mpoly_derivative,
@@ -40,6 +42,7 @@ from flint.flintlib.functions.fmpq_mpoly cimport (
     fmpq_mpoly_get_term_coeff_fmpq,
     fmpq_mpoly_get_term_exp_fmpz,
     fmpq_mpoly_integral,
+    fmpq_mpoly_is_canonical,
     fmpq_mpoly_is_one,
     fmpq_mpoly_is_zero,
     fmpq_mpoly_length,
@@ -1119,6 +1122,22 @@ cdef class fmpq_mpoly(flint_mpoly):
         fmpz_mpoly_deflation(shift.val, stride.val, self.val.zpoly, self.ctx.val.zctx)
         return list(stride), list(shift)
 
+    cdef _compose_gens_(self, ctx, slong *mapping):
+        cdef fmpq_mpoly res = create_fmpq_mpoly(ctx)
+        fmpq_mpoly_compose_fmpq_mpoly_gen(
+            res.val,
+            self.val,
+            mapping,
+            self.ctx.val,
+            (<fmpq_mpoly_ctx>ctx).val
+        )
+
+        if not fmpq_mpoly_is_canonical(res.val, res.ctx.val):
+            fmpq_mpoly_sort_terms(res.val, res.ctx.val)
+            fmpq_mpoly_combine_like_terms(res.val, res.ctx.val)
+
+        return res
+
 
 cdef class fmpq_mpoly_vec:
     """
diff --git a/src/flint/types/fmpz_mod_mpoly.pyx b/src/flint/types/fmpz_mod_mpoly.pyx
index de20cad9..13effe20 100644
--- a/src/flint/types/fmpz_mod_mpoly.pyx
+++ b/src/flint/types/fmpz_mod_mpoly.pyx
@@ -18,7 +18,9 @@ from flint.flintlib.functions.fmpz_mod_mpoly cimport (
     fmpz_mod_mpoly_add,
     fmpz_mod_mpoly_add_fmpz,
     fmpz_mod_mpoly_clear,
+    fmpz_mod_mpoly_combine_like_terms,
     fmpz_mod_mpoly_compose_fmpz_mod_mpoly,
+    fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen,
     fmpz_mod_mpoly_ctx_get_modulus,
     fmpz_mod_mpoly_ctx_init,
     fmpz_mod_mpoly_deflate,
@@ -40,6 +42,7 @@ from flint.flintlib.functions.fmpz_mod_mpoly cimport (
     fmpz_mod_mpoly_get_term_coeff_fmpz,
     fmpz_mod_mpoly_get_term_exp_fmpz,
     fmpz_mod_mpoly_inflate,
+    fmpz_mod_mpoly_is_canonical,
     fmpz_mod_mpoly_is_one,
     fmpz_mod_mpoly_is_zero,
     fmpz_mod_mpoly_length,
@@ -1136,6 +1139,22 @@ cdef class fmpz_mod_mpoly(flint_mpoly):
         fmpz_mod_mpoly_deflation(shift.val, stride.val, self.val, self.ctx.val)
         return list(stride), list(shift)
 
+    cdef _compose_gens_(self, ctx, slong *mapping):
+        cdef fmpz_mod_mpoly res = create_fmpz_mod_mpoly(ctx)
+        fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(
+            res.val,
+            self.val,
+            mapping,
+            self.ctx.val,
+            (<fmpz_mod_mpoly_ctx>ctx).val
+        )
+
+        if not fmpz_mod_mpoly_is_canonical(res.val, res.ctx.val):
+            fmpz_mod_mpoly_sort_terms(res.val, res.ctx.val)
+            fmpz_mod_mpoly_combine_like_terms(res.val, res.ctx.val)
+
+        return res
+
 
 cdef class fmpz_mod_mpoly_vec:
     """
diff --git a/src/flint/types/fmpz_mpoly.pyx b/src/flint/types/fmpz_mpoly.pyx
index e5cb1962..d2bc70d6 100644
--- a/src/flint/types/fmpz_mpoly.pyx
+++ b/src/flint/types/fmpz_mpoly.pyx
@@ -21,7 +21,9 @@ from flint.flintlib.functions.fmpz_mpoly cimport (
     fmpz_mpoly_buchberger_naive,
     fmpz_mpoly_buchberger_naive_with_limits,
     fmpz_mpoly_clear,
+    fmpz_mpoly_combine_like_terms,
     fmpz_mpoly_compose_fmpz_mpoly,
+    fmpz_mpoly_compose_fmpz_mpoly_gen,
     fmpz_mpoly_ctx_init,
     fmpz_mpoly_deflate,
     fmpz_mpoly_deflation,
@@ -43,6 +45,7 @@ from flint.flintlib.functions.fmpz_mpoly cimport (
     fmpz_mpoly_get_term_exp_fmpz,
     fmpz_mpoly_inflate,
     fmpz_mpoly_integral,
+    fmpz_mpoly_is_canonical,
     fmpz_mpoly_is_one,
     fmpz_mpoly_is_zero,
     fmpz_mpoly_length,
@@ -686,12 +689,14 @@ cdef class fmpz_mpoly(flint_mpoly):
 
     def degrees(self):
         """
-        Return a dictionary of variable name to degree.
+        Return a tuple of degrees.
 
             >>> ctx = fmpz_mpoly_ctx.get(('x', 4), 'lex')
-            >>> p = ctx.from_dict({(1, 0, 0, 0): 1, (0, 2, 0, 0): 2, (0, 0, 3, 0): 3})
+            >>> p = sum(x**(2 * i) for i, x in enumerate(ctx.gens()))
+            >>> p
+            x1 + x2^2 + x3^3 + 1
             >>> p.degrees()
-            (1, 2, 3, 0)
+            (0, 1, 2, 3)
         """
         cdef:
             slong nvars = self.ctx.nvars()
@@ -946,32 +951,21 @@ cdef class fmpz_mpoly(flint_mpoly):
         fmpz_mpoly_factor_clear(fac, self.ctx.val)
         return c, res
 
-    # TODO: Rethink context conversions, particularly the proposed methods in #132
-    # def coerce_to_context(self, ctx):
-    #     cdef:
-    #         fmpz_mpoly res
-    #         slong *C
-    #         slong i
-
-    #     if not typecheck(ctx, fmpz_mpoly_ctx):
-    #         raise ValueError("provided context is not a fmpz_mpoly_ctx")
-
-    #     if self.ctx is ctx:
-    #         return self
-
-    #     C = <slong *> libc.stdlib.malloc(self.ctx.val.minfo.nvars * sizeof(slong *))
-    #     if C is NULL:
-    #         raise MemoryError("malloc returned a null pointer")
-    #     res = create_fmpz_mpoly(self.ctx)
-
-    #     vars = {x: i for i, x in enumerate(ctx.py_names)}
-    #     for i, var in enumerate(self.ctx.py_names):
-    #         C[i] = <slong>vars[var]
+    cdef _compose_gens_(self, ctx, slong *mapping):
+        cdef fmpz_mpoly res = create_fmpz_mpoly(ctx)
+        fmpz_mpoly_compose_fmpz_mpoly_gen(
+            res.val,
+            self.val,
+            mapping,
+            self.ctx.val,
+            (<fmpz_mpoly_ctx>ctx).val
+        )
 
-    #     fmpz_mpoly_compose_fmpz_mpoly_gen(res.val, self.val, C, self.ctx.val, (<fmpz_mpoly_ctx>ctx).val)
+        if not fmpz_mpoly_is_canonical(res.val, res.ctx.val):
+            fmpz_mpoly_sort_terms(res.val, res.ctx.val)
+            fmpz_mpoly_combine_like_terms(res.val, res.ctx.val)
 
-    #     libc.stdlib.free(C)
-    #     return res
+        return res
 
     def derivative(self, var):
         """
diff --git a/src/flint/types/nmod_mpoly.pyx b/src/flint/types/nmod_mpoly.pyx
index d9de8791..f9b3c98e 100644
--- a/src/flint/types/nmod_mpoly.pyx
+++ b/src/flint/types/nmod_mpoly.pyx
@@ -21,6 +21,8 @@ from flint.flintlib.functions.nmod_mpoly cimport (
     nmod_mpoly_add,
     nmod_mpoly_add_ui,
     nmod_mpoly_clear,
+    nmod_mpoly_combine_like_terms,
+    nmod_mpoly_compose_nmod_mpoly_gen,
     nmod_mpoly_compose_nmod_mpoly,
     nmod_mpoly_ctx_init,
     nmod_mpoly_ctx_modulus,
@@ -40,6 +42,7 @@ from flint.flintlib.functions.nmod_mpoly cimport (
     nmod_mpoly_get_str_pretty,
     nmod_mpoly_get_term_coeff_ui,
     nmod_mpoly_get_term_exp_fmpz,
+    nmod_mpoly_is_canonical,
     nmod_mpoly_is_one,
     nmod_mpoly_is_zero,
     nmod_mpoly_length,
@@ -1114,6 +1117,22 @@ cdef class nmod_mpoly(flint_mpoly):
         nmod_mpoly_deflation(shift.val, stride.val, self.val, self.ctx.val)
         return list(stride), list(shift)
 
+    cdef _compose_gens_(self, ctx, slong *mapping):
+        cdef nmod_mpoly res = create_nmod_mpoly(ctx)
+        nmod_mpoly_compose_nmod_mpoly_gen(
+            res.val,
+            self.val,
+            mapping,
+            self.ctx.val,
+            (<nmod_mpoly_ctx>ctx).val
+        )
+
+        if not nmod_mpoly_is_canonical(res.val, res.ctx.val):
+            nmod_mpoly_sort_terms(res.val, res.ctx.val)
+            nmod_mpoly_combine_like_terms(res.val, res.ctx.val)
+
+        return res
+
 
 cdef class nmod_mpoly_vec:
     """

From 446503613dff1d365ba077f7a7ff83ab57681dc0 Mon Sep 17 00:00:00 2001
From: Jake-Moss <jake.moss@uqconnect.edu.au>
Date: Tue, 17 Sep 2024 00:28:35 +1000
Subject: [PATCH 02/15] Add flint version guard to fmpz_mod_mpoly._compose_gen

---
 src/flint/flint_base/flint_base.pyx | 19 ++++++++++---------
 src/flint/flintlib/types/flint.pxd  |  7 ++++---
 src/flint/types/fmpz_mod_mpoly.pyx  |  7 +++++++
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index 68aa1c5f..bb5bfb12 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -950,7 +950,7 @@ cdef class flint_mpoly(flint_elem):
         )
         return new_ctx, self.coerce_to_context(new_ctx)
 
-    def coerce_to_context(self, ctx, mapping: dict[str | int, str | int] = None):
+    def coerce_to_context(self, other_ctx, mapping: dict[str | int, str | int] = None):
         """
         Coerce this polynomial to a different context.
 
@@ -975,23 +975,24 @@ cdef class flint_mpoly(flint_elem):
             slong *c_mapping
             slong i
 
-        if not typecheck(ctx, type(self.ctx)):
+        ctx = self.context()
+        if not typecheck(other_ctx, type(ctx)):
             raise ValueError(
-                f"provided context is not a {self.ctx.__class__.__name__}"
+                f"provided context is not a {ctx.__class__.__name__}"
             )
-        elif self.ctx is ctx:
+        elif ctx is other_ctx:
             return self
 
         if mapping is None:
-            mapping = self.ctx.infer_generator_mapping(ctx)
+            mapping = ctx.infer_generator_mapping(other_ctx)
         else:
             mapping = {
-                self.ctx.variable_to_index(k): ctx.variable_to_index(v)
+                ctx.variable_to_index(k): ctx.variable_to_index(v)
                 for k, v in mapping.items()
             }
 
         try:
-            c_mapping = <slong *> libc.stdlib.malloc(self.ctx.nvars() * sizeof(slong *))
+            c_mapping = <slong *> libc.stdlib.malloc(ctx.nvars() * sizeof(slong *))
             if c_mapping is NULL:
                 raise MemoryError("malloc returned a null pointer")
 
@@ -1001,11 +1002,11 @@ cdef class flint_mpoly(flint_elem):
             for k, v in mapping.items():
                 c_mapping[k] = <slong>v
 
-            return self._compose_gens_(ctx, c_mapping)
+            return self._compose_gens_(other_ctx, c_mapping)
         finally:
             libc.stdlib.free(c_mapping)
 
-    cdef _compose_gens_(self, ctx, slong *mapping):
+    cdef _compose_gens_(self, other_ctx, slong *mapping):
         raise NotImplementedError("abstract method")
 
 
diff --git a/src/flint/flintlib/types/flint.pxd b/src/flint/flintlib/types/flint.pxd
index 120bf1da..feb1a848 100644
--- a/src/flint/flintlib/types/flint.pxd
+++ b/src/flint/flintlib/types/flint.pxd
@@ -45,14 +45,15 @@ cdef extern from "flint/fmpz.h":
 
 cdef extern from *:
     """
-    /*
-     * Functions renamed in Flint 3.2.0
-     */
     #if __FLINT_RELEASE < 30200 /* Flint < 3.2.0 */
 
+    /* Functions renamed in Flint 3.2.0 */
     #define flint_rand_init flint_randinit
     #define flint_rand_clear flint_randclear
 
+    /* Functions added in Flint 3.2.0 */
+    #define fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(...) (void)0
+
     #endif
     """
 
diff --git a/src/flint/types/fmpz_mod_mpoly.pyx b/src/flint/types/fmpz_mod_mpoly.pyx
index 13effe20..85b05cb5 100644
--- a/src/flint/types/fmpz_mod_mpoly.pyx
+++ b/src/flint/types/fmpz_mod_mpoly.pyx
@@ -4,6 +4,7 @@ from flint.flint_base.flint_base cimport (
     ordering_py_to_c,
     ordering_c_to_py,
 )
+from flint.flint_base.flint_base import FLINT_RELEASE, FLINT_VERSION
 
 from flint.utils.typecheck cimport typecheck
 from flint.utils.flint_exceptions import DomainError, IncompatibleContextError
@@ -1140,6 +1141,12 @@ cdef class fmpz_mod_mpoly(flint_mpoly):
         return list(stride), list(shift)
 
     cdef _compose_gens_(self, ctx, slong *mapping):
+        if FLINT_RELEASE < 30200:
+            raise NotImplementedError(
+                "this function is not supported below FLINT 3.2.0, "
+                f"current version is {FLINT_VERSION}"
+            )
+
         cdef fmpz_mod_mpoly res = create_fmpz_mod_mpoly(ctx)
         fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(
             res.val,

From 8119b563d41b18f2897f3cc7513f63de2fd46aad Mon Sep 17 00:00:00 2001
From: Jake Moss <jake.moss@student.uq.edu.au>
Date: Tue, 17 Sep 2024 14:48:57 +1000
Subject: [PATCH 03/15] Doc fixes and typos in `coerce_to_context`

---
 src/flint/flint_base/flint_base.pyx | 4 ++--
 src/flint/types/fmpq_mpoly.pyx      | 6 ++++--
 src/flint/types/fmpz_mod_mpoly.pyx  | 6 ++++--
 src/flint/types/fmpz_mpoly.pyx      | 6 +-----
 src/flint/types/nmod_mpoly.pyx      | 6 ++++--
 5 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index bb5bfb12..1a84d592 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -987,7 +987,7 @@ cdef class flint_mpoly(flint_elem):
             mapping = ctx.infer_generator_mapping(other_ctx)
         else:
             mapping = {
-                ctx.variable_to_index(k): ctx.variable_to_index(v)
+                ctx.variable_to_index(k): other_ctx.variable_to_index(v)
                 for k, v in mapping.items()
             }
 
@@ -996,7 +996,7 @@ cdef class flint_mpoly(flint_elem):
             if c_mapping is NULL:
                 raise MemoryError("malloc returned a null pointer")
 
-            for i in range(self.ctx.nvars()):
+            for i in range(ctx.nvars()):
                 c_mapping[i] = <slong>-1
 
             for k, v in mapping.items():
diff --git a/src/flint/types/fmpq_mpoly.pyx b/src/flint/types/fmpq_mpoly.pyx
index 80ec0009..9431e1ad 100644
--- a/src/flint/types/fmpq_mpoly.pyx
+++ b/src/flint/types/fmpq_mpoly.pyx
@@ -702,9 +702,11 @@ cdef class fmpq_mpoly(flint_mpoly):
         Return a dictionary of variable name to degree.
 
             >>> ctx = fmpq_mpoly_ctx.get(('x', 4), 'lex')
-            >>> p = ctx.from_dict({(1, 0, 0, 0): 1, (0, 2, 0, 0): 2, (0, 0, 3, 0): 3})
+            >>> p = sum(x**i for i, x in enumerate(ctx.gens()))
+            >>> p
+            x1 + x2^2 + x3^3 + 1
             >>> p.degrees()
-            (1, 2, 3, 0)
+            (0, 1, 2, 3)
         """
         cdef:
             slong nvars = self.ctx.nvars()
diff --git a/src/flint/types/fmpz_mod_mpoly.pyx b/src/flint/types/fmpz_mod_mpoly.pyx
index 85b05cb5..ac21611e 100644
--- a/src/flint/types/fmpz_mod_mpoly.pyx
+++ b/src/flint/types/fmpz_mod_mpoly.pyx
@@ -707,9 +707,11 @@ cdef class fmpz_mod_mpoly(flint_mpoly):
         Return a dictionary of variable name to degree.
 
             >>> ctx = fmpz_mod_mpoly_ctx.get(('x', 4), 11, 'lex')
-            >>> p = ctx.from_dict({(1, 0, 0, 0): 1, (0, 2, 0, 0): 2, (0, 0, 3, 0): 3})
+            >>> p = sum(x**i for i, x in enumerate(ctx.gens()))
+            >>> p
+            x1 + x2^2 + x3^3 + 1
             >>> p.degrees()
-            (1, 2, 3, 0)
+            (0, 1, 2, 3)
         """
         cdef:
             slong nvars = self.ctx.nvars()
diff --git a/src/flint/types/fmpz_mpoly.pyx b/src/flint/types/fmpz_mpoly.pyx
index d2bc70d6..770a470d 100644
--- a/src/flint/types/fmpz_mpoly.pyx
+++ b/src/flint/types/fmpz_mpoly.pyx
@@ -692,7 +692,7 @@ cdef class fmpz_mpoly(flint_mpoly):
         Return a tuple of degrees.
 
             >>> ctx = fmpz_mpoly_ctx.get(('x', 4), 'lex')
-            >>> p = sum(x**(2 * i) for i, x in enumerate(ctx.gens()))
+            >>> p = sum(x**i for i, x in enumerate(ctx.gens()))
             >>> p
             x1 + x2^2 + x3^3 + 1
             >>> p.degrees()
@@ -961,10 +961,6 @@ cdef class fmpz_mpoly(flint_mpoly):
             (<fmpz_mpoly_ctx>ctx).val
         )
 
-        if not fmpz_mpoly_is_canonical(res.val, res.ctx.val):
-            fmpz_mpoly_sort_terms(res.val, res.ctx.val)
-            fmpz_mpoly_combine_like_terms(res.val, res.ctx.val)
-
         return res
 
     def derivative(self, var):
diff --git a/src/flint/types/nmod_mpoly.pyx b/src/flint/types/nmod_mpoly.pyx
index f9b3c98e..849b6cc3 100644
--- a/src/flint/types/nmod_mpoly.pyx
+++ b/src/flint/types/nmod_mpoly.pyx
@@ -687,9 +687,11 @@ cdef class nmod_mpoly(flint_mpoly):
         Return a dictionary of variable name to degree.
 
             >>> ctx = nmod_mpoly_ctx.get(('x', 4), 11, 'lex')
-            >>> p = ctx.from_dict({(1, 0, 0, 0): 1, (0, 2, 0, 0): 2, (0, 0, 3, 0): 3})
+            >>> p = sum(x**i for i, x in enumerate(ctx.gens()))
+            >>> p
+            x1 + x2^2 + x3^3 + 1
             >>> p.degrees()
-            (1, 2, 3, 0)
+            (0, 1, 2, 3)
         """
         cdef:
             slong nvars = self.ctx.nvars()

From d4a0a745e6020dce277972fecd3f57410f01a7ad Mon Sep 17 00:00:00 2001
From: Jake Moss <jake.moss@student.uq.edu.au>
Date: Tue, 17 Sep 2024 15:00:00 +1000
Subject: [PATCH 04/15] Flint does the normalisation itself, not sure why it
 didn't earlier

---
 src/flint/flint_base/flint_base.pyx | 2 --
 src/flint/types/fmpq_mpoly.pyx      | 6 ------
 src/flint/types/fmpz_mod_mpoly.pyx  | 6 ------
 src/flint/types/fmpz_mpoly.pyx      | 2 --
 src/flint/types/nmod_mpoly.pyx      | 6 ------
 5 files changed, 22 deletions(-)

diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index 1a84d592..82e2808d 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -959,8 +959,6 @@ cdef class flint_mpoly(flint_elem):
         of the generators. Generators with names that are not found within the other
         context are mapped to 0. The mapping can be explicitly provided.
 
-        The resulting polynomial is also normalised.
-
             >>> from flint import fmpz_mpoly_ctx
             >>> ctx = fmpz_mpoly_ctx.get(('x', 'y', 'a', 'b'))
             >>> ctx2 = fmpz_mpoly_ctx.get(('a', 'b'))
diff --git a/src/flint/types/fmpq_mpoly.pyx b/src/flint/types/fmpq_mpoly.pyx
index 9431e1ad..ced7c625 100644
--- a/src/flint/types/fmpq_mpoly.pyx
+++ b/src/flint/types/fmpq_mpoly.pyx
@@ -20,7 +20,6 @@ from flint.flintlib.functions.fmpq_mpoly cimport (
     fmpq_mpoly_add,
     fmpq_mpoly_add_fmpq,
     fmpq_mpoly_clear,
-    fmpq_mpoly_combine_like_terms,
     fmpq_mpoly_compose_fmpq_mpoly,
     fmpq_mpoly_compose_fmpq_mpoly_gen,
     fmpq_mpoly_ctx_init,
@@ -42,7 +41,6 @@ from flint.flintlib.functions.fmpq_mpoly cimport (
     fmpq_mpoly_get_term_coeff_fmpq,
     fmpq_mpoly_get_term_exp_fmpz,
     fmpq_mpoly_integral,
-    fmpq_mpoly_is_canonical,
     fmpq_mpoly_is_one,
     fmpq_mpoly_is_zero,
     fmpq_mpoly_length,
@@ -1134,10 +1132,6 @@ cdef class fmpq_mpoly(flint_mpoly):
             (<fmpq_mpoly_ctx>ctx).val
         )
 
-        if not fmpq_mpoly_is_canonical(res.val, res.ctx.val):
-            fmpq_mpoly_sort_terms(res.val, res.ctx.val)
-            fmpq_mpoly_combine_like_terms(res.val, res.ctx.val)
-
         return res
 
 
diff --git a/src/flint/types/fmpz_mod_mpoly.pyx b/src/flint/types/fmpz_mod_mpoly.pyx
index ac21611e..b824b2dc 100644
--- a/src/flint/types/fmpz_mod_mpoly.pyx
+++ b/src/flint/types/fmpz_mod_mpoly.pyx
@@ -19,7 +19,6 @@ from flint.flintlib.functions.fmpz_mod_mpoly cimport (
     fmpz_mod_mpoly_add,
     fmpz_mod_mpoly_add_fmpz,
     fmpz_mod_mpoly_clear,
-    fmpz_mod_mpoly_combine_like_terms,
     fmpz_mod_mpoly_compose_fmpz_mod_mpoly,
     fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen,
     fmpz_mod_mpoly_ctx_get_modulus,
@@ -43,7 +42,6 @@ from flint.flintlib.functions.fmpz_mod_mpoly cimport (
     fmpz_mod_mpoly_get_term_coeff_fmpz,
     fmpz_mod_mpoly_get_term_exp_fmpz,
     fmpz_mod_mpoly_inflate,
-    fmpz_mod_mpoly_is_canonical,
     fmpz_mod_mpoly_is_one,
     fmpz_mod_mpoly_is_zero,
     fmpz_mod_mpoly_length,
@@ -1158,10 +1156,6 @@ cdef class fmpz_mod_mpoly(flint_mpoly):
             (<fmpz_mod_mpoly_ctx>ctx).val
         )
 
-        if not fmpz_mod_mpoly_is_canonical(res.val, res.ctx.val):
-            fmpz_mod_mpoly_sort_terms(res.val, res.ctx.val)
-            fmpz_mod_mpoly_combine_like_terms(res.val, res.ctx.val)
-
         return res
 
 
diff --git a/src/flint/types/fmpz_mpoly.pyx b/src/flint/types/fmpz_mpoly.pyx
index 770a470d..512258d5 100644
--- a/src/flint/types/fmpz_mpoly.pyx
+++ b/src/flint/types/fmpz_mpoly.pyx
@@ -21,7 +21,6 @@ from flint.flintlib.functions.fmpz_mpoly cimport (
     fmpz_mpoly_buchberger_naive,
     fmpz_mpoly_buchberger_naive_with_limits,
     fmpz_mpoly_clear,
-    fmpz_mpoly_combine_like_terms,
     fmpz_mpoly_compose_fmpz_mpoly,
     fmpz_mpoly_compose_fmpz_mpoly_gen,
     fmpz_mpoly_ctx_init,
@@ -45,7 +44,6 @@ from flint.flintlib.functions.fmpz_mpoly cimport (
     fmpz_mpoly_get_term_exp_fmpz,
     fmpz_mpoly_inflate,
     fmpz_mpoly_integral,
-    fmpz_mpoly_is_canonical,
     fmpz_mpoly_is_one,
     fmpz_mpoly_is_zero,
     fmpz_mpoly_length,
diff --git a/src/flint/types/nmod_mpoly.pyx b/src/flint/types/nmod_mpoly.pyx
index 849b6cc3..2506c46a 100644
--- a/src/flint/types/nmod_mpoly.pyx
+++ b/src/flint/types/nmod_mpoly.pyx
@@ -21,7 +21,6 @@ from flint.flintlib.functions.nmod_mpoly cimport (
     nmod_mpoly_add,
     nmod_mpoly_add_ui,
     nmod_mpoly_clear,
-    nmod_mpoly_combine_like_terms,
     nmod_mpoly_compose_nmod_mpoly_gen,
     nmod_mpoly_compose_nmod_mpoly,
     nmod_mpoly_ctx_init,
@@ -42,7 +41,6 @@ from flint.flintlib.functions.nmod_mpoly cimport (
     nmod_mpoly_get_str_pretty,
     nmod_mpoly_get_term_coeff_ui,
     nmod_mpoly_get_term_exp_fmpz,
-    nmod_mpoly_is_canonical,
     nmod_mpoly_is_one,
     nmod_mpoly_is_zero,
     nmod_mpoly_length,
@@ -1129,10 +1127,6 @@ cdef class nmod_mpoly(flint_mpoly):
             (<nmod_mpoly_ctx>ctx).val
         )
 
-        if not nmod_mpoly_is_canonical(res.val, res.ctx.val):
-            nmod_mpoly_sort_terms(res.val, res.ctx.val)
-            nmod_mpoly_combine_like_terms(res.val, res.ctx.val)
-
         return res
 
 

From 9d572f1f0d4949d15c0a564586aaa9f72fadc99c Mon Sep 17 00:00:00 2001
From: Jake Moss <jake.moss@student.uq.edu.au>
Date: Tue, 17 Sep 2024 16:09:56 +1000
Subject: [PATCH 05/15] Just disable the method all the time. Set ordering is
 not stable

---
 src/flint/flint_base/flint_base.pyx | 7 +++++--
 src/flint/flintlib/types/flint.pxd  | 7 ++++---
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index 82e2808d..e8708c6a 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -430,7 +430,7 @@ cdef class flint_mpoly_context(flint_elem):
         """
         return cls.get(
             names=ctx.names() if names is None else names,
-            ordering=ctx.ordering() if ordering is None else names,
+            ordering=ctx.ordering() if ordering is None else ordering,
         )
 
     def _any_as_scalar(self, other):
@@ -493,8 +493,11 @@ cdef class flint_mpoly_context(flint_elem):
             >>> from flint import fmpz_mpoly_ctx
             >>> ctx = fmpz_mpoly_ctx.get(('x', 'y', 'z', 'a', 'b'))
             >>> ctx2 = fmpz_mpoly_ctx.get(('b', 'a'))
-            >>> ctx.infer_generator_mapping(ctx2)
+            >>> mapping = ctx.infer_generator_mapping(ctx2)
+            >>> mapping  # doctest: +SKIP
             {3: 1, 4: 0}
+            >>> list(sorted(mapping.items()))  # Set ordering is not stable
+            [(3, 1), (4, 0)]
         """
         gens_to_idxs = {x: i for i, x in enumerate(self.names())}
         other_gens_to_idxs = {x: i for i, x in enumerate(ctx.names())}
diff --git a/src/flint/flintlib/types/flint.pxd b/src/flint/flintlib/types/flint.pxd
index 83672f00..2a79bff0 100644
--- a/src/flint/flintlib/types/flint.pxd
+++ b/src/flint/flintlib/types/flint.pxd
@@ -51,10 +51,11 @@ cdef extern from *:
     #define flint_rand_init flint_randinit
     #define flint_rand_clear flint_randclear
 
-    /* Functions added in Flint 3.2.0 */
-    #define fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(...) (void)0
-
     #endif
+
+    /* FIXME: add version guard when https://github.com/flintlib/flint/pull/2068 */
+    /* is resolved */
+    #define fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(...) (void)0
     """
 
 cdef extern from "flint/flint.h":

From 4ea2ba867a7cb3604d621e57eca1718f276510b0 Mon Sep 17 00:00:00 2001
From: Jake Moss <jake.moss@student.uq.edu.au>
Date: Tue, 17 Sep 2024 16:56:32 +1000
Subject: [PATCH 06/15] Add new tests, use `.names()` over `.py_names` directly

---
 src/flint/flint_base/flint_base.pyx |  3 ++-
 src/flint/test/test_all.py          | 42 ++++++++++++++++++++++++-----
 2 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index e8708c6a..80d53337 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -478,10 +478,11 @@ cdef class flint_mpoly_context(flint_elem):
         if len(gens) > nvars:
             raise ValueError(f"expected at most {nvars} unique generators, got {len(gens)}")
 
+        names = self.names()
         remaining_gens = []
         for i in range(nvars):
             if i not in gen_idxs:
-                remaining_gens.append(self.py_names[i])
+                remaining_gens.append(names[i])
 
         return self.from_context(self, names=remaining_gens)
 
diff --git a/src/flint/test/test_all.py b/src/flint/test/test_all.py
index 3d64e712..2dba5ed3 100644
--- a/src/flint/test/test_all.py
+++ b/src/flint/test/test_all.py
@@ -2861,6 +2861,12 @@ def test_mpolys():
 
         ctx = get_context(("x", 2))
 
+        def mpoly(x):
+            return ctx.from_dict(x)
+
+        def quick_poly():
+            return mpoly({(0, 0): 1, (0, 1): 2, (1, 0): 3, (2, 2): 4})
+
         assert raises(lambda : ctx.__class__("x", flint.Ordering.lex), RuntimeError)
         assert raises(lambda: get_context(("x", 2), ordering="bad"), ValueError)
         assert raises(lambda: get_context(("x", -1)), ValueError)
@@ -2877,17 +2883,41 @@ def test_mpolys():
         assert raises(lambda: P(val={"bad": 1}, ctx=None), ValueError)
         assert raises(lambda: P(val="1", ctx=None), ValueError)
 
+        ctx1 = get_context(("x", 4))
+        ctx2 = get_context(("x", 4), ordering="deglex")
+        assert ctx1.drop_gens(*ctx1.names()).names() == tuple()
+        assert ctx1.drop_gens(ctx1.name(1), ctx1.name(2)).names() == (ctx1.name(0), ctx1.name(3))
+        assert ctx1.drop_gens().names() == ctx1.names()
+        assert ctx1.drop_gens(-1).names() == ctx1.names()[:-1]
+
+        assert ctx.infer_generator_mapping(ctx) == {i: i for i in range(ctx.nvars())}
+        assert ctx1.infer_generator_mapping(ctx) == {0: 0, 1: 1}
+        assert ctx1.drop_gens(*ctx.names()).infer_generator_mapping(ctx) == {}
+
+        # FIXME: Remove this guard when https://github.com/flintlib/flint/pull/2068 is
+        # resolved
+        if P is not flint.fmpz_mod_mpoly:
+            assert quick_poly().coerce_to_context(ctx1) == \
+                ctx1.from_dict(
+                    {(0, 0, 0, 0): 1, (0, 1, 0, 0): 2, (1, 0, 0, 0): 3, (2, 2, 0, 0): 4}
+                )
+            assert quick_poly().coerce_to_context(ctx1).drop_unused_gens() == (ctx, quick_poly())
+
+            new_ctx, new_poly = quick_poly().coerce_to_context(ctx2).drop_unused_gens()
+            assert new_ctx != ctx
+            assert new_poly != quick_poly()
+
+            new_ctx = new_ctx.from_context(new_ctx, ordering=ctx.ordering())
+            assert new_ctx == ctx
+            assert new_poly.coerce_to_context(new_ctx) == quick_poly()
+        else:
+            assert raises(lambda: quick_poly().coerce_to_context(ctx1), NotImplementedError)
+
         assert P(val={(0, 0): 1}, ctx=ctx) == ctx.from_dict({(0, 0): 1})
         assert P(ctx=ctx).context() == ctx
         assert P(1, ctx=ctx).is_one()
         assert ctx.gen(1) == ctx.from_dict({(0, 1): 1})
 
-        def mpoly(x):
-            return ctx.from_dict(x)
-
-        def quick_poly():
-            return mpoly({(0, 0): 1, (0, 1): 2, (1, 0): 3, (2, 2): 4})
-
         assert ctx.nvars() == 2
         assert ctx.ordering() == flint.Ordering.lex
 

From aa2901ab1c43fc38f2871bb7eff40477e69e0b2c Mon Sep 17 00:00:00 2001
From: Jake Moss <jake.moss@student.uq.edu.au>
Date: Tue, 17 Sep 2024 17:01:54 +1000
Subject: [PATCH 07/15] Add `append_gens` method

---
 src/flint/flint_base/flint_base.pyx | 11 +++++++++++
 src/flint/test/test_all.py          |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index 80d53337..89898c89 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -486,6 +486,17 @@ cdef class flint_mpoly_context(flint_elem):
 
         return self.from_context(self, names=remaining_gens)
 
+    def append_gens(self, *gens: str):
+        """
+        Get a context with the specified generators appended.
+
+            >>> from flint import fmpz_mpoly_ctx
+            >>> ctx = fmpz_mpoly_ctx.get(('x', 'y', 'z'))
+            >>> ctx.append_gens('a', 'b')
+            fmpz_mpoly_ctx(5, '<Ordering.lex: 'lex'>', ('x', 'y', 'z', 'a', 'b'))
+        """
+        return self.from_context(self, names=self.names() + gens)
+
     def infer_generator_mapping(self, ctx: flint_mpoly_context):
         """
         Infer a mapping of generator indexes from this contexts generators, to the
diff --git a/src/flint/test/test_all.py b/src/flint/test/test_all.py
index 2dba5ed3..9c3241b4 100644
--- a/src/flint/test/test_all.py
+++ b/src/flint/test/test_all.py
@@ -2910,6 +2910,8 @@ def quick_poly():
             new_ctx = new_ctx.from_context(new_ctx, ordering=ctx.ordering())
             assert new_ctx == ctx
             assert new_poly.coerce_to_context(new_ctx) == quick_poly()
+
+            assert ctx.append_gens(*ctx1.names()[-2:]) == ctx1
         else:
             assert raises(lambda: quick_poly().coerce_to_context(ctx1), NotImplementedError)
 

From e8cdeaf991eea3bc521e4dc3ac749fddc90fc927 Mon Sep 17 00:00:00 2001
From: Jake Moss <jake.moss@student.uq.edu.au>
Date: Tue, 17 Sep 2024 17:11:53 +1000
Subject: [PATCH 08/15] Unconditionally raise `NotImplementedError`

---
 src/flint/types/fmpz_mod_mpoly.pyx | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/flint/types/fmpz_mod_mpoly.pyx b/src/flint/types/fmpz_mod_mpoly.pyx
index b824b2dc..e57f43a2 100644
--- a/src/flint/types/fmpz_mod_mpoly.pyx
+++ b/src/flint/types/fmpz_mod_mpoly.pyx
@@ -1141,11 +1141,10 @@ cdef class fmpz_mod_mpoly(flint_mpoly):
         return list(stride), list(shift)
 
     cdef _compose_gens_(self, ctx, slong *mapping):
-        if FLINT_RELEASE < 30200:
-            raise NotImplementedError(
-                "this function is not supported below FLINT 3.2.0, "
-                f"current version is {FLINT_VERSION}"
-            )
+        raise NotImplementedError(
+            "this function is not supported below FLINT 3.2.0, "
+            f"current version is {FLINT_VERSION}"
+        )
 
         cdef fmpz_mod_mpoly res = create_fmpz_mod_mpoly(ctx)
         fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(

From 93de55af9f413f8ec9e5282b42329e67271309bb Mon Sep 17 00:00:00 2001
From: Jake Moss <jake.moss@student.uq.edu.au>
Date: Tue, 17 Sep 2024 17:15:39 +1000
Subject: [PATCH 09/15] Linting

---
 src/flint/types/fmpz_mod_mpoly.pyx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/flint/types/fmpz_mod_mpoly.pyx b/src/flint/types/fmpz_mod_mpoly.pyx
index e57f43a2..cd3eadfb 100644
--- a/src/flint/types/fmpz_mod_mpoly.pyx
+++ b/src/flint/types/fmpz_mod_mpoly.pyx
@@ -4,7 +4,7 @@ from flint.flint_base.flint_base cimport (
     ordering_py_to_c,
     ordering_c_to_py,
 )
-from flint.flint_base.flint_base import FLINT_RELEASE, FLINT_VERSION
+from flint.flint_base.flint_base import FLINT_VERSION
 
 from flint.utils.typecheck cimport typecheck
 from flint.utils.flint_exceptions import DomainError, IncompatibleContextError

From ce1a966bf1075114bd30b77b4d639eb0e98f115f Mon Sep 17 00:00:00 2001
From: Jake-Moss <jake.moss@uqconnect.edu.au>
Date: Mon, 23 Sep 2024 00:31:18 +1000
Subject: [PATCH 10/15] Rename `coerce_to_context` -> `project_to_context`

---
 src/flint/flint_base/flint_base.pyx | 8 ++++----
 src/flint/types/fmpz_mod_mpoly.pyx  | 2 +-
 src/flint/types/nmod_mpoly.pyx      | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index 89898c89..3c82faac 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -965,9 +965,9 @@ cdef class flint_mpoly(flint_elem):
         )
         return new_ctx, self.coerce_to_context(new_ctx)
 
-    def coerce_to_context(self, other_ctx, mapping: dict[str | int, str | int] = None):
+    def project_to_context(self, other_ctx, mapping: dict[str | int, str | int] = None):
         """
-        Coerce this polynomial to a different context.
+        Project this polynomial to a different context.
 
         This is equivalent to composing this polynomial with the generators of another
         context. By default the mapping between contexts is inferred based on the name
@@ -979,9 +979,9 @@ cdef class flint_mpoly(flint_elem):
             >>> ctx2 = fmpz_mpoly_ctx.get(('a', 'b'))
             >>> x, y, a, b = ctx.gens()
             >>> f = x + 2*y + 3*a + 4*b
-            >>> f.coerce_to_context(ctx2)
+            >>> f.project_to_context(ctx2)
             3*a + 4*b
-            >>> f.coerce_to_context(ctx2, mapping={"x": "a", "b": 0})
+            >>> f.project_to_context(ctx2, mapping={"x": "a", "b": 0})
             5*a
         """
         cdef:
diff --git a/src/flint/types/fmpz_mod_mpoly.pyx b/src/flint/types/fmpz_mod_mpoly.pyx
index cd3eadfb..c68002d6 100644
--- a/src/flint/types/fmpz_mod_mpoly.pyx
+++ b/src/flint/types/fmpz_mod_mpoly.pyx
@@ -949,7 +949,7 @@ cdef class fmpz_mod_mpoly(flint_mpoly):
         return c, res
 
     # TODO: Rethink context conversions, particularly the proposed methods in #132
-    # def coerce_to_context(self, ctx):
+    # def project_to_context(self, ctx):
     #     cdef:
     #         fmpz_mod_mpoly res
     #         slong *C
diff --git a/src/flint/types/nmod_mpoly.pyx b/src/flint/types/nmod_mpoly.pyx
index 2506c46a..43131cf0 100644
--- a/src/flint/types/nmod_mpoly.pyx
+++ b/src/flint/types/nmod_mpoly.pyx
@@ -927,7 +927,7 @@ cdef class nmod_mpoly(flint_mpoly):
         return constant, res
 
     # TODO: Rethink context conversions, particularly the proposed methods in #132
-    # def coerce_to_context(self, ctx):
+    # def project_to_context(self, ctx):
     #     cdef:
     #         nmod_mpoly res
     #         slong *C

From 324f6aed9d06e001a7e01b78de3322361da4c1fa Mon Sep 17 00:00:00 2001
From: Jake-Moss <jake.moss@uqconnect.edu.au>
Date: Mon, 23 Sep 2024 00:34:43 +1000
Subject: [PATCH 11/15] Require a single arg instead of *args to make composing
 nicer

---
 src/flint/flint_base/flint_base.pyx | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index 3c82faac..8e24c51d 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -463,13 +463,13 @@ cdef class flint_mpoly_context(flint_elem):
             exp_vec = (0,) * self.nvars()
         return self.from_dict({tuple(exp_vec): coeff})
 
-    def drop_gens(self, *gens: str | int):
+    def drop_gens(self, gens: Iterable[str | int]):
         """
         Get a context with the specified generators removed.
 
             >>> from flint import fmpz_mpoly_ctx
             >>> ctx = fmpz_mpoly_ctx.get(('x', 'y', 'z', 'a', 'b'))
-            >>> ctx.drop_gens('x', -2)
+            >>> ctx.drop_gens(('x', -2))
             fmpz_mpoly_ctx(3, '<Ordering.lex: 'lex'>', ('y', 'z', 'b'))
         """
         nvars = self.nvars()

From 737d22cfde4a3994834cad596b182ff647254705 Mon Sep 17 00:00:00 2001
From: Jake-Moss <jake.moss@uqconnect.edu.au>
Date: Mon, 23 Sep 2024 00:35:11 +1000
Subject: [PATCH 12/15] Replace `drop_unused_gens` with `unused_gens`

---
 src/flint/flint_base/flint_base.pyx | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/src/flint/flint_base/flint_base.pyx b/src/flint/flint_base/flint_base.pyx
index 8e24c51d..16564b12 100644
--- a/src/flint/flint_base/flint_base.pyx
+++ b/src/flint/flint_base/flint_base.pyx
@@ -941,10 +941,9 @@ cdef class flint_mpoly(flint_elem):
         """
         return zip(self.monoms(), self.coeffs())
 
-    def drop_unused_gens(self):
+    def unused_gens(self):
         """
-        Remove unused generators from this polynomial. Returns a potentially new
-        context, and potentially new polynomial.
+        Report the unused generators from this polynomial.
 
         A generator is unused if it's maximum degree is 0.
 
@@ -954,16 +953,11 @@ cdef class flint_mpoly(flint_elem):
             >>> f = sum(ctx.gens()[1:3])
             >>> f
             x1 + x2
-            >>> new_ctx, new_f = f.drop_unused_gens()
-            >>> new_ctx
-            fmpz_mpoly_ctx(2, '<Ordering.lex: 'lex'>', ('x1', 'x2'))
-            >>> new_f
-            x1 + x2
+            >>> f.unused_gens()
+            ('x0', 'x3')
         """
-        new_ctx = self.context().drop_gens(
-            *(i for i, x in enumerate(self.degrees()) if not x)
-        )
-        return new_ctx, self.coerce_to_context(new_ctx)
+        names = self.context().names()
+        return tuple(names[i] for i, x in enumerate(self.degrees()) if not x)
 
     def project_to_context(self, other_ctx, mapping: dict[str | int, str | int] = None):
         """

From 77f4bc07d0b005c4248032018b9c260667873892 Mon Sep 17 00:00:00 2001
From: Jake-Moss <jake.moss@uqconnect.edu.au>
Date: Mon, 23 Sep 2024 00:52:01 +1000
Subject: [PATCH 13/15] Update tests

---
 src/flint/test/test_all.py | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/flint/test/test_all.py b/src/flint/test/test_all.py
index 9c3241b4..e69a12f9 100644
--- a/src/flint/test/test_all.py
+++ b/src/flint/test/test_all.py
@@ -2885,35 +2885,38 @@ def quick_poly():
 
         ctx1 = get_context(("x", 4))
         ctx2 = get_context(("x", 4), ordering="deglex")
-        assert ctx1.drop_gens(*ctx1.names()).names() == tuple()
-        assert ctx1.drop_gens(ctx1.name(1), ctx1.name(2)).names() == (ctx1.name(0), ctx1.name(3))
-        assert ctx1.drop_gens().names() == ctx1.names()
-        assert ctx1.drop_gens(-1).names() == ctx1.names()[:-1]
+        assert ctx1.drop_gens(ctx1.names()).names() == tuple()
+        assert ctx1.drop_gens((ctx1.name(1), ctx1.name(2))).names() == (ctx1.name(0), ctx1.name(3))
+        assert ctx1.drop_gens(tuple()).names() == ctx1.names()
+        assert ctx1.drop_gens((-1,)).names() == ctx1.names()[:-1]
 
         assert ctx.infer_generator_mapping(ctx) == {i: i for i in range(ctx.nvars())}
         assert ctx1.infer_generator_mapping(ctx) == {0: 0, 1: 1}
-        assert ctx1.drop_gens(*ctx.names()).infer_generator_mapping(ctx) == {}
+        assert ctx1.drop_gens(ctx.names()).infer_generator_mapping(ctx) == {}
 
         # FIXME: Remove this guard when https://github.com/flintlib/flint/pull/2068 is
         # resolved
         if P is not flint.fmpz_mod_mpoly:
-            assert quick_poly().coerce_to_context(ctx1) == \
+            assert quick_poly().project_to_context(ctx1) == \
                 ctx1.from_dict(
                     {(0, 0, 0, 0): 1, (0, 1, 0, 0): 2, (1, 0, 0, 0): 3, (2, 2, 0, 0): 4}
                 )
-            assert quick_poly().coerce_to_context(ctx1).drop_unused_gens() == (ctx, quick_poly())
+            new_poly = quick_poly().project_to_context(ctx1)
+            assert ctx1.drop_gens(new_poly.unused_gens()) == ctx
+            assert new_poly.project_to_context(ctx) == quick_poly()
 
-            new_ctx, new_poly = quick_poly().coerce_to_context(ctx2).drop_unused_gens()
+            new_poly = quick_poly().project_to_context(ctx2)
+            new_ctx = ctx2.drop_gens(new_poly.unused_gens())
             assert new_ctx != ctx
             assert new_poly != quick_poly()
 
             new_ctx = new_ctx.from_context(new_ctx, ordering=ctx.ordering())
             assert new_ctx == ctx
-            assert new_poly.coerce_to_context(new_ctx) == quick_poly()
+            assert new_poly.project_to_context(new_ctx) == quick_poly()
 
             assert ctx.append_gens(*ctx1.names()[-2:]) == ctx1
         else:
-            assert raises(lambda: quick_poly().coerce_to_context(ctx1), NotImplementedError)
+            assert raises(lambda: quick_poly().project_to_context(ctx1), NotImplementedError)
 
         assert P(val={(0, 0): 1}, ctx=ctx) == ctx.from_dict({(0, 0): 1})
         assert P(ctx=ctx).context() == ctx

From f0ca6506b5da118d4718da5e7edb158950c983e4 Mon Sep 17 00:00:00 2001
From: Jake-Moss <jake.moss@uqconnect.edu.au>
Date: Mon, 23 Sep 2024 00:52:13 +1000
Subject: [PATCH 14/15] Remove commented out methods

---
 src/flint/types/fmpq_mpoly.pyx     | 22 --------------
 src/flint/types/fmpz_mod_mpoly.pyx | 49 ------------------------------
 src/flint/types/fmpz_mpoly.pyx     | 22 --------------
 src/flint/types/nmod_mpoly.pyx     | 49 ------------------------------
 4 files changed, 142 deletions(-)

diff --git a/src/flint/types/fmpq_mpoly.pyx b/src/flint/types/fmpq_mpoly.pyx
index ced7c625..2cc586c4 100644
--- a/src/flint/types/fmpq_mpoly.pyx
+++ b/src/flint/types/fmpq_mpoly.pyx
@@ -548,28 +548,6 @@ cdef class fmpq_mpoly(flint_mpoly):
 
         return res
 
-    # def terms(self):
-    #     """
-    #     Return the terms of this polynomial as a list of fmpq_mpolys.
-
-    #         >>> ctx = fmpq_mpoly_ctx.get(('x', 2), 'lex')
-    #         >>> f = ctx.from_dict({(0, 0): 1, (1, 0): 2, (0, 1): 3, (1, 1): 4})
-    #         >>> f.terms()
-    #         [4*x0*x1, 2*x0, 3*x1, 1]
-
-    #     """
-    #     cdef:
-    #         fmpq_mpoly term
-    #         slong i
-
-    #     res = []
-    #     for i in range(len(self)):
-    #         term = create_fmpq_mpoly(self.ctx)
-    #         fmpq_mpoly_get_term(term.val, self.val, i, self.ctx.val)
-    #         res.append(term)
-
-    #     return res
-
     def subs(self, dict_args) -> fmpq_mpoly:
         """
         Partial evaluate this polynomial with select constants. Keys must be generator names or generator indices,
diff --git a/src/flint/types/fmpz_mod_mpoly.pyx b/src/flint/types/fmpz_mod_mpoly.pyx
index c68002d6..2a3bd2b8 100644
--- a/src/flint/types/fmpz_mod_mpoly.pyx
+++ b/src/flint/types/fmpz_mod_mpoly.pyx
@@ -556,28 +556,6 @@ cdef class fmpz_mod_mpoly(flint_mpoly):
 
         return res
 
-    # def terms(self):
-    #     """
-    #     Return the terms of this polynomial as a list of fmpz_mod_mpolys.
-
-    #         >>> ctx = fmpz_mod_mpoly_ctx.get(('x', 2), 11, 'lex')
-    #         >>> f = ctx.from_dict({(0, 0): 1, (1, 0): 2, (0, 1): 3, (1, 1): 4})
-    #         >>> f.terms()
-    #         [4*x0*x1, 2*x0, 3*x1, 1]
-
-    #     """
-    #     cdef:
-    #         fmpz_mod_mpoly term
-    #         slong i
-
-    #     res = []
-    #     for i in range(len(self)):
-    #         term = create_fmpz_mod_mpoly(self.ctx)
-    #         fmpz_mod_mpoly_get_term(term.val, self.val, i, self.ctx.val)
-    #         res.append(term)
-
-    #     return res
-
     def subs(self, dict_args) -> fmpz_mod_mpoly:
         """
         Partial evaluate this polynomial with select constants. Keys must be generator names or generator indices,
@@ -948,33 +926,6 @@ cdef class fmpz_mod_mpoly(flint_mpoly):
         fmpz_mod_mpoly_factor_clear(fac, self.ctx.val)
         return c, res
 
-    # TODO: Rethink context conversions, particularly the proposed methods in #132
-    # def project_to_context(self, ctx):
-    #     cdef:
-    #         fmpz_mod_mpoly res
-    #         slong *C
-    #         slong i
-
-    #     if not typecheck(ctx, fmpz_mod_mpoly_ctx):
-    #         raise ValueError("provided context is not a fmpz_mod_mpoly_ctx")
-
-    #     if self.ctx is ctx:
-    #         return self
-
-    #     C = <slong *> libc.stdlib.malloc(self.ctx.val.minfo.nvars * sizeof(slong *))
-    #     if C is NULL:
-    #         raise MemoryError("malloc returned a null pointer")
-    #     res = create_fmpz_mod_mpoly(self.ctx)
-
-    #     vars = {x: i for i, x in enumerate(ctx.py_names)}
-    #     for i, var in enumerate(self.ctx.py_names):
-    #         C[i] = <slong>vars[var]
-
-    #     fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(res.val, self.val, C, self.ctx.val, (<fmpz_mod_mpoly_ctx>ctx).val)
-
-    #     libc.stdlib.free(C)
-    #     return res
-
     def derivative(self, var):
         """
         Return the derivative of this polynomial with respect to the provided variable.
diff --git a/src/flint/types/fmpz_mpoly.pyx b/src/flint/types/fmpz_mpoly.pyx
index 512258d5..61fce82a 100644
--- a/src/flint/types/fmpz_mpoly.pyx
+++ b/src/flint/types/fmpz_mpoly.pyx
@@ -538,28 +538,6 @@ cdef class fmpz_mpoly(flint_mpoly):
 
         return res
 
-    # def terms(self):
-    #     """
-    #     Return the terms of this polynomial as a list of fmpz_mpolys.
-
-    #         >>> ctx = fmpz_mpoly_ctx.get(('x', 2), 'lex')
-    #         >>> f = ctx.from_dict({(0, 0): 1, (1, 0): 2, (0, 1): 3, (1, 1): 4})
-    #         >>> f.terms()
-    #         [4*x0*x1, 2*x0, 3*x1, 1]
-
-    #     """
-    #     cdef:
-    #         fmpz_mpoly term
-    #         slong i
-
-    #     res = []
-    #     for i in range(len(self)):
-    #         term = create_fmpz_mpoly(self.ctx)
-    #         fmpz_mpoly_get_term(term.val, self.val, i, self.ctx.val)
-    #         res.append(term)
-
-    #     return res
-
     def subs(self, dict_args) -> fmpz_mpoly:
         """
         Partial evaluate this polynomial with select constants. Keys must be generator names or generator indices,
diff --git a/src/flint/types/nmod_mpoly.pyx b/src/flint/types/nmod_mpoly.pyx
index 43131cf0..c3723747 100644
--- a/src/flint/types/nmod_mpoly.pyx
+++ b/src/flint/types/nmod_mpoly.pyx
@@ -539,28 +539,6 @@ cdef class nmod_mpoly(flint_mpoly):
         """
         return [nmod_mpoly_get_term_coeff_ui(self.val, i, self.ctx.val) for i in range(len(self))]
 
-    # def terms(self):
-    #     """
-    #     Return the terms of this polynomial as a list of nmod_mpolys.
-
-    #         >>> ctx = nmod_mpoly_ctx.get(('x', 2), 11, 'lex')
-    #         >>> f = ctx.from_dict({(0, 0): 1, (1, 0): 2, (0, 1): 3, (1, 1): 4})
-    #         >>> f.terms()
-    #         [4*x0*x1, 2*x0, 3*x1, 1]
-
-    #     """
-    #     cdef:
-    #         nmod_mpoly term
-    #         slong i
-
-    #     res = []
-    #     for i in range(len(self)):
-    #         term = create_nmod_mpoly(self.ctx)
-    #         nmod_mpoly_get_term(term.val, self.val, i, self.ctx.val)
-    #         res.append(term)
-
-    #     return res
-
     def subs(self, dict_args) -> nmod_mpoly:
         """
         Partial evaluate this polynomial with select constants. Keys must be generator names or generator indices,
@@ -926,33 +904,6 @@ cdef class nmod_mpoly(flint_mpoly):
         nmod_mpoly_factor_clear(fac, self.ctx.val)
         return constant, res
 
-    # TODO: Rethink context conversions, particularly the proposed methods in #132
-    # def project_to_context(self, ctx):
-    #     cdef:
-    #         nmod_mpoly res
-    #         slong *C
-    #         slong i
-
-    #     if not typecheck(ctx, nmod_mpoly_ctx):
-    #         raise ValueError("provided context is not a nmod_mpoly_ctx")
-
-    #     if self.ctx is ctx:
-    #         return self
-
-    #     C = <slong *> libc.stdlib.malloc(self.ctx.val.minfo.nvars * sizeof(slong *))
-    #     if C is NULL:
-    #         raise MemoryError("malloc returned a null pointer")
-    #     res = create_nmod_mpoly(self.ctx)
-
-    #     vars = {x: i for i, x in enumerate(ctx.py_names)}
-    #     for i, var in enumerate(self.ctx.py_names):
-    #         C[i] = <slong>vars[var]
-
-    #     nmod_mpoly_compose_nmod_mpoly_gen(res.val, self.val, C, self.ctx.val, (<nmod_mpoly_ctx>ctx).val)
-
-    #     libc.stdlib.free(C)
-    #     return res
-
     def derivative(self, var):
         """
         Return the derivative of this polynomial with respect to the provided variable.

From d1a14383997279d96402cdc6d13d4fc17562a5ea Mon Sep 17 00:00:00 2001
From: Jake-Moss <jake.moss@uqconnect.edu.au>
Date: Mon, 23 Sep 2024 01:07:21 +1000
Subject: [PATCH 15/15] Add `fmpz_mod_mpoly` workaround

---
 src/flint/test/test_all.py         | 41 +++++++++++++-----------------
 src/flint/types/fmpz_mod_mpoly.pyx | 38 +++++++++++++++------------
 2 files changed, 40 insertions(+), 39 deletions(-)

diff --git a/src/flint/test/test_all.py b/src/flint/test/test_all.py
index e69a12f9..6d5f19aa 100644
--- a/src/flint/test/test_all.py
+++ b/src/flint/test/test_all.py
@@ -2894,29 +2894,24 @@ def quick_poly():
         assert ctx1.infer_generator_mapping(ctx) == {0: 0, 1: 1}
         assert ctx1.drop_gens(ctx.names()).infer_generator_mapping(ctx) == {}
 
-        # FIXME: Remove this guard when https://github.com/flintlib/flint/pull/2068 is
-        # resolved
-        if P is not flint.fmpz_mod_mpoly:
-            assert quick_poly().project_to_context(ctx1) == \
-                ctx1.from_dict(
-                    {(0, 0, 0, 0): 1, (0, 1, 0, 0): 2, (1, 0, 0, 0): 3, (2, 2, 0, 0): 4}
-                )
-            new_poly = quick_poly().project_to_context(ctx1)
-            assert ctx1.drop_gens(new_poly.unused_gens()) == ctx
-            assert new_poly.project_to_context(ctx) == quick_poly()
-
-            new_poly = quick_poly().project_to_context(ctx2)
-            new_ctx = ctx2.drop_gens(new_poly.unused_gens())
-            assert new_ctx != ctx
-            assert new_poly != quick_poly()
-
-            new_ctx = new_ctx.from_context(new_ctx, ordering=ctx.ordering())
-            assert new_ctx == ctx
-            assert new_poly.project_to_context(new_ctx) == quick_poly()
-
-            assert ctx.append_gens(*ctx1.names()[-2:]) == ctx1
-        else:
-            assert raises(lambda: quick_poly().project_to_context(ctx1), NotImplementedError)
+        assert quick_poly().project_to_context(ctx1) == \
+            ctx1.from_dict(
+                {(0, 0, 0, 0): 1, (0, 1, 0, 0): 2, (1, 0, 0, 0): 3, (2, 2, 0, 0): 4}
+            )
+        new_poly = quick_poly().project_to_context(ctx1)
+        assert ctx1.drop_gens(new_poly.unused_gens()) == ctx
+        assert new_poly.project_to_context(ctx) == quick_poly()
+
+        new_poly = quick_poly().project_to_context(ctx2)
+        new_ctx = ctx2.drop_gens(new_poly.unused_gens())
+        assert new_ctx != ctx
+        assert new_poly != quick_poly()
+
+        new_ctx = new_ctx.from_context(new_ctx, ordering=ctx.ordering())
+        assert new_ctx == ctx
+        assert new_poly.project_to_context(new_ctx) == quick_poly()
+
+        assert ctx.append_gens(*ctx1.names()[-2:]) == ctx1
 
         assert P(val={(0, 0): 1}, ctx=ctx) == ctx.from_dict({(0, 0): 1})
         assert P(ctx=ctx).context() == ctx
diff --git a/src/flint/types/fmpz_mod_mpoly.pyx b/src/flint/types/fmpz_mod_mpoly.pyx
index 2a3bd2b8..5ecb01ad 100644
--- a/src/flint/types/fmpz_mod_mpoly.pyx
+++ b/src/flint/types/fmpz_mod_mpoly.pyx
@@ -4,7 +4,6 @@ from flint.flint_base.flint_base cimport (
     ordering_py_to_c,
     ordering_c_to_py,
 )
-from flint.flint_base.flint_base import FLINT_VERSION
 
 from flint.utils.typecheck cimport typecheck
 from flint.utils.flint_exceptions import DomainError, IncompatibleContextError
@@ -20,7 +19,7 @@ from flint.flintlib.functions.fmpz_mod_mpoly cimport (
     fmpz_mod_mpoly_add_fmpz,
     fmpz_mod_mpoly_clear,
     fmpz_mod_mpoly_compose_fmpz_mod_mpoly,
-    fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen,
+    # fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen,
     fmpz_mod_mpoly_ctx_get_modulus,
     fmpz_mod_mpoly_ctx_init,
     fmpz_mod_mpoly_deflate,
@@ -71,6 +70,8 @@ from flint.flintlib.functions.fmpz_mod_mpoly_factor cimport (
     fmpz_mod_mpoly_factor_t,
 )
 
+from flint.types.fmpz_mpoly cimport fmpz_mpoly_ctx, fmpz_mpoly
+
 from cpython.object cimport Py_EQ, Py_NE
 cimport libc.stdlib
 
@@ -1092,21 +1093,26 @@ cdef class fmpz_mod_mpoly(flint_mpoly):
         return list(stride), list(shift)
 
     cdef _compose_gens_(self, ctx, slong *mapping):
-        raise NotImplementedError(
-            "this function is not supported below FLINT 3.2.0, "
-            f"current version is {FLINT_VERSION}"
-        )
-
-        cdef fmpz_mod_mpoly res = create_fmpz_mod_mpoly(ctx)
-        fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(
-            res.val,
-            self.val,
-            mapping,
-            self.ctx.val,
-            (<fmpz_mod_mpoly_ctx>ctx).val
-        )
+        # FIXME: Remove this when https://github.com/flintlib/flint/pull/2068 is
+        # resolved
+
+        # cdef fmpz_mod_mpoly res = create_fmpz_mod_mpoly(ctx)
+        # fmpz_mod_mpoly_compose_fmpz_mod_mpoly_gen(
+        #     res.val,
+        #     self.val,
+        #     mapping,
+        #     self.ctx.val,
+        #     (<fmpz_mod_mpoly_ctx>ctx).val
+        # )
 
-        return res
+        cdef:
+            fmpz_mpoly_ctx mpoly_ctx = fmpz_mpoly_ctx.from_context(self.context())
+            fmpz_mpoly_ctx res_ctx = fmpz_mpoly_ctx.from_context(ctx)
+
+            fmpz_mpoly poly = mpoly_ctx.from_dict(self.to_dict())
+            fmpz_mpoly res = poly._compose_gens_(res_ctx, mapping)
+
+        return ctx.from_dict(res.to_dict())
 
 
 cdef class fmpz_mod_mpoly_vec: