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[Bridges] add CountAtLeastToCountBelongsBridge (#1920)
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‎docs/src/submodules/Bridges/list_of_bridges.md‎

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@@ -53,6 +53,7 @@ Bridges.Constraint.SemiToBinaryBridge
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Bridges.Constraint.ZeroOneBridge
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Bridges.Constraint.AllDifferentToCountDistinctBridge
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Bridges.Constraint.BinPackingToMILPBridge
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Bridges.Constraint.CountAtLeastToCountBelongsBridge
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Bridges.Constraint.CountBelongsToMILPBridge
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Bridges.Constraint.CountDistinctToMILPBridge
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Bridges.Constraint.TableToMILPBridge

‎src/Bridges/Constraint/Constraint.jl‎

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@@ -20,6 +20,7 @@ include("single_bridge_optimizer.jl")
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include("bridges/all_different.jl")
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include("bridges/bin_packing.jl")
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include("bridges/count_at_least.jl")
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include("bridges/count_belongs.jl")
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include("bridges/count_distinct.jl")
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include("bridges/det.jl")
@@ -99,6 +100,7 @@ function add_all_bridges(bridged_model, ::Type{T}) where {T}
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# TODO(odow): this reformulation assumes the bins are numbered 1..N. We
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# should fix this to use the variable bounds before adding automatically.
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# MOI.Bridges.add_bridge(bridged_model, BinPackingToMILPBridge{T})
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MOI.Bridges.add_bridge(bridged_model, CountAtLeastToCountBelongsBridge{T})
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MOI.Bridges.add_bridge(bridged_model, CountBelongsToMILPBridge{T})
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MOI.Bridges.add_bridge(bridged_model, CountDistinctToMILPBridge{T})
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MOI.Bridges.add_bridge(bridged_model, TableToMILPBridge{T})

‎src/Bridges/Constraint/bridges/count_at_least.jl‎

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# Copyright (c) 2017: Miles Lubin and contributors
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# Copyright (c) 2017: Google Inc.
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#
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# Use of this source code is governed by an MIT-style license that can be found
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# in the LICENSE.md file or at https://opensource.org/licenses/MIT.
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"""
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CountAtLeastToCountBelongsBridge{T,F} <: Bridges.Constraint.AbstractBridge
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`CountAtLeastToCountBelongsBridge` implements the following reformulation:
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* ``x \\in \\textsf{CountAtLeast}(n, d, set)`` to
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``(n_i, x_{d_i}) \\in \\textsf{CountBelongs}(1+d)``
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and ``\\sum\\limits n_i \\ge n``
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## Source node
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`CountAtLeastToCountBelongsBridge` supports:
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* `F` in [`MOI.CountAtLeast`](@ref)
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where `F` is [`MOI.VectorOfVariables`](@ref) or
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[`MOI.VectorAffineFunction{T}`](@ref).
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## Target nodes
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`CountAtLeastToCountBelongsBridge` creates:
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* `F` in [`MOI.CountBelongs`](@ref)
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* [`MOI.ScalarAffineFunction{T}`](@ref) in [`MOI.GreaterThan{T}`](@ref)
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"""
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mutable struct CountAtLeastToCountBelongsBridge{
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T,
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F<:Union{MOI.VectorOfVariables,MOI.VectorAffineFunction{T}},
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} <: AbstractBridge
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f::F
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s::MOI.CountAtLeast
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variables::Vector{MOI.VariableIndex}
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ci::Vector{MOI.ConstraintIndex{F,MOI.CountBelongs}}
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count::MOI.ConstraintIndex{MOI.ScalarAffineFunction{T},MOI.GreaterThan{T}}
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end
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const CountAtLeastToCountBelongs{T,OT<:MOI.ModelLike} =
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SingleBridgeOptimizer{CountAtLeastToCountBelongsBridge{T},OT}
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function bridge_constraint(
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::Type{CountAtLeastToCountBelongsBridge{T,F}},
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model::MOI.ModelLike,
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f::F,
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s::MOI.CountAtLeast,
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) where {T,F<:Union{MOI.VectorOfVariables,MOI.VectorAffineFunction{T}}}
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x = collect(MOI.Utilities.eachscalar(f))
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variables = MOI.VariableIndex[]
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cis = MOI.ConstraintIndex{F,MOI.CountBelongs}[]
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count_f = MOI.ScalarAffineFunction(MOI.ScalarAffineTerm{T}[], zero(T))
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offset = 0
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for p in s.partitions
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indices = offset .+ (1:p)
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y = MOI.add_variable(model)
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push!(variables, y)
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push!(count_f.terms, MOI.ScalarAffineTerm(one(T), y))
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ci = MOI.add_constraint(
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model,
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MOI.Utilities.operate(vcat, T, y, x[indices]...),
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MOI.CountBelongs(1 + p, s.set),
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)
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push!(cis, ci)
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offset += p
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end
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count = MOI.add_constraint(model, count_f, MOI.GreaterThan(T(s.n)))
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return CountAtLeastToCountBelongsBridge{T,F}(f, s, variables, cis, count)
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end
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function MOI.supports_constraint(
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::Type{<:CountAtLeastToCountBelongsBridge{T}},
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::Type{<:Union{MOI.VectorOfVariables,MOI.VectorAffineFunction{T}}},
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::Type{MOI.CountAtLeast},
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) where {T}
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return true
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end
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function MOI.Bridges.added_constrained_variable_types(
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::Type{<:CountAtLeastToCountBelongsBridge},
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)
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return Tuple{Type}[]
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end
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function MOI.Bridges.added_constraint_types(
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::Type{CountAtLeastToCountBelongsBridge{T,F}},
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) where {T,F}
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return Tuple{Type,Type}[
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(F, MOI.CountBelongs),
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(MOI.ScalarAffineFunction{T}, MOI.GreaterThan{T}),
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]
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end
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function concrete_bridge_type(
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::Type{<:CountAtLeastToCountBelongsBridge{T}},
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::Type{F},
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::Type{MOI.CountAtLeast},
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) where {T,F<:Union{MOI.VectorOfVariables,MOI.VectorAffineFunction{T}}}
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return CountAtLeastToCountBelongsBridge{T,F}
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end
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function MOI.get(
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::MOI.ModelLike,
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::MOI.ConstraintFunction,
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bridge::CountAtLeastToCountBelongsBridge,
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)
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return bridge.f
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end
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function MOI.get(
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::MOI.ModelLike,
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::MOI.ConstraintSet,
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bridge::CountAtLeastToCountBelongsBridge,
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)
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return bridge.s
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end
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function MOI.delete(
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model::MOI.ModelLike,
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bridge::CountAtLeastToCountBelongsBridge,
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)
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for ci in bridge.ci
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MOI.delete(model, ci)
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end
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MOI.delete(model, bridge.count)
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for x in bridge.variables
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MOI.delete(model, x)
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end
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return
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end
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function MOI.get(
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bridge::CountAtLeastToCountBelongsBridge,
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::MOI.NumberOfVariables,
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)::Int64
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return length(bridge.variables)
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end
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function MOI.get(
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bridge::CountAtLeastToCountBelongsBridge,
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::MOI.ListOfVariableIndices,
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)::Vector{MOI.VariableIndex}
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return copy(bridge.variables)
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end
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function MOI.get(
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bridge::CountAtLeastToCountBelongsBridge{T,F},
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::MOI.NumberOfConstraints{F,MOI.CountBelongs},
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)::Int64 where {T,F}
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return length(bridge.ci)
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end
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function MOI.get(
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bridge::CountAtLeastToCountBelongsBridge{T,F},
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::MOI.ListOfConstraintIndices{F,MOI.CountBelongs},
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) where {T,F}
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return copy(bridge.ci)
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end
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function MOI.get(
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::CountAtLeastToCountBelongsBridge{T,F},
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::MOI.NumberOfConstraints{MOI.ScalarAffineFunction{T},MOI.GreaterThan{T}},
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)::Int64 where {T,F}
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return 1
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end
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function MOI.get(
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bridge::CountAtLeastToCountBelongsBridge{T,F},
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::MOI.ListOfConstraintIndices{
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MOI.ScalarAffineFunction{T},
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MOI.GreaterThan{T},
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},
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) where {T,F}
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return [bridge.count]
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end

‎test/Bridges/Constraint/count_at_least.jl‎

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# Copyright (c) 2017: Miles Lubin and contributors
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# Copyright (c) 2017: Google Inc.
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#
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# Use of this source code is governed by an MIT-style license that can be found
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# in the LICENSE.md file or at https://opensource.org/licenses/MIT.
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module TestConstraintCountAtLeast
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using Test
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using MathOptInterface
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const MOI = MathOptInterface
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function runtests()
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for name in names(@__MODULE__; all = true)
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if startswith("$(name)", "test_")
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@testset "$(name)" begin
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getfield(@__MODULE__, name)()
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end
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end
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end
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return
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end
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function test_runtests_VectorOfVariables()
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MOI.Bridges.runtests(
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MOI.Bridges.Constraint.CountAtLeastToCountBelongsBridge,
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"""
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variables: a, b, c
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[a, b, b, c] in CountAtLeast(1, [2, 2], Set([3]))
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a in Interval(1.0, 3.0)
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b in Interval(1.0, 3.0)
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c in Interval(1.0, 3.0)
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""",
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"""
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variables: a, b, c, y1, y2
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[y1, a, b] in CountBelongs(3, Set([3]))
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[y2, b, c] in CountBelongs(3, Set([3]))
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y1 + y2 >= 1.0
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a in Interval(1.0, 3.0)
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b in Interval(1.0, 3.0)
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c in Interval(1.0, 3.0)
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""",
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)
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return
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end
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function test_runtests_VectorAffineFunction()
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MOI.Bridges.runtests(
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MOI.Bridges.Constraint.CountAtLeastToCountBelongsBridge,
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"""
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variables: a, b, c
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[1.0 * a, b + 1.0, b, c] in CountAtLeast(1, [2, 2], Set([3]))
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a in Interval(1.0, 3.0)
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b in Interval(1.0, 3.0)
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c in Interval(1.0, 3.0)
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""",
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"""
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variables: a, b, c, y1, y2
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[y1, 1.0 * a, b + 1.0] in CountBelongs(3, Set([3]))
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[y2, 1.0 * b, 1.0 * c] in CountBelongs(3, Set([3]))
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y1 + y2 >= 1.0
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a in Interval(1.0, 3.0)
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b in Interval(1.0, 3.0)
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c in Interval(1.0, 3.0)
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""",
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)
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return
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end
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end # module
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TestConstraintCountAtLeast.runtests()

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