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| 1 | +# Copyright (c) 2017: Miles Lubin and contributors |
| 2 | +# Copyright (c) 2017: Google Inc. |
| 3 | +# |
| 4 | +# Use of this source code is governed by an MIT-style license that can be found |
| 5 | +# in the LICENSE.md file or at https://opensource.org/licenses/MIT. |
| 6 | + |
| 7 | +""" |
| 8 | + ExponentialConeToScalarNonlinearFunctionBridge{T,F} <: |
| 9 | + Bridges.Constraint.AbstractBridge |
| 10 | +
|
| 11 | +`ExponentialConeToScalarNonlinearFunctionBridge` implements the following |
| 12 | +reformulation: |
| 13 | +
|
| 14 | + * ``(x, y, z) \\in \\textsf{ExponentialCone}()`` to |
| 15 | + ``y \\cdot exp(x / y)) - z \\le 0``, ``y \\ge 0``. |
| 16 | +
|
| 17 | +## Source node |
| 18 | +
|
| 19 | +`ExponentialConeToScalarNonlinearFunctionBridge` supports: |
| 20 | +
|
| 21 | + * `F` in [`MOI.ExponentialCone`](@ref) |
| 22 | +
|
| 23 | +## Target nodes |
| 24 | +
|
| 25 | +`ExponentialConeToScalarNonlinearFunctionBridge` creates: |
| 26 | +
|
| 27 | + * [`MOI.ScalarNonlinearFunction`](@ref) in [`MOI.LessThan{T}`](@ref) |
| 28 | + * [`MOI.ScalarAffineFunction`](@ref) in [`MOI.GreaterThan{T}`](@ref) |
| 29 | +""" |
| 30 | +mutable struct ExponentialConeToScalarNonlinearFunctionBridge{ |
| 31 | + T, |
| 32 | + F<:Union{MOI.VectorOfVariables,MOI.VectorAffineFunction{T}}, |
| 33 | +} <: AbstractBridge |
| 34 | + f::F |
| 35 | + ci::MOI.ConstraintIndex{MOI.ScalarNonlinearFunction,MOI.LessThan{T}} |
| 36 | + ci_y::MOI.ConstraintIndex{MOI.ScalarAffineFunction{T},MOI.GreaterThan{T}} |
| 37 | +end |
| 38 | + |
| 39 | +const ExponentialToScalarNonlinearFunction{T,OT<:MOI.ModelLike} = |
| 40 | + SingleBridgeOptimizer{ExponentialConeToScalarNonlinearFunctionBridge{T},OT} |
| 41 | + |
| 42 | +function bridge_constraint( |
| 43 | + ::Type{ExponentialConeToScalarNonlinearFunctionBridge{T,F}}, |
| 44 | + model::MOI.ModelLike, |
| 45 | + f::F, |
| 46 | + s::MOI.ExponentialCone, |
| 47 | +) where {T,F<:Union{MOI.VectorOfVariables,MOI.VectorAffineFunction{T}}} |
| 48 | + x, y, z = MOI.Utilities.scalarize(f) |
| 49 | + g_x_div_y = MOI.ScalarNonlinearFunction(:/, Any[x, y]) |
| 50 | + g_exp_x_div_y = MOI.ScalarNonlinearFunction(:exp, Any[g_x_div_y]) |
| 51 | + g = MOI.ScalarNonlinearFunction( |
| 52 | + :-, |
| 53 | + Any[MOI.ScalarNonlinearFunction(:*, Any[y, g_exp_x_div_y]), z], |
| 54 | + ) |
| 55 | + ci = MOI.add_constraint(model, g, MOI.LessThan(zero(T))) |
| 56 | + ci_y = MOI.add_constraint(model, one(T) * y, MOI.GreaterThan(zero(T))) |
| 57 | + return ExponentialConeToScalarNonlinearFunctionBridge{T,F}(f, ci, ci_y) |
| 58 | +end |
| 59 | + |
| 60 | +function MOI.supports_constraint( |
| 61 | + ::Type{<:ExponentialConeToScalarNonlinearFunctionBridge{T}}, |
| 62 | + ::Type{<:Union{MOI.VectorOfVariables,MOI.VectorAffineFunction{T}}}, |
| 63 | + ::Type{MOI.ExponentialCone}, |
| 64 | +) where {T} |
| 65 | + return true |
| 66 | +end |
| 67 | + |
| 68 | +function MOI.Bridges.added_constrained_variable_types( |
| 69 | + ::Type{ExponentialConeToScalarNonlinearFunctionBridge{T,F}}, |
| 70 | +) where {T,F} |
| 71 | + return Tuple{Type}[] |
| 72 | +end |
| 73 | + |
| 74 | +function MOI.Bridges.added_constraint_types( |
| 75 | + ::Type{ExponentialConeToScalarNonlinearFunctionBridge{T,F}}, |
| 76 | +) where {T,F} |
| 77 | + return Tuple{Type,Type}[ |
| 78 | + (MOI.ScalarNonlinearFunction, MOI.LessThan{T}), |
| 79 | + (MOI.ScalarAffineFunction{T}, MOI.GreaterThan{T}), |
| 80 | + ] |
| 81 | +end |
| 82 | + |
| 83 | +function concrete_bridge_type( |
| 84 | + ::Type{<:ExponentialConeToScalarNonlinearFunctionBridge{T}}, |
| 85 | + ::Type{F}, |
| 86 | + ::Type{MOI.ExponentialCone}, |
| 87 | +) where {T,F<:Union{MOI.VectorOfVariables,MOI.VectorAffineFunction{T}}} |
| 88 | + return ExponentialConeToScalarNonlinearFunctionBridge{T,F} |
| 89 | +end |
| 90 | + |
| 91 | +function MOI.get( |
| 92 | + ::MOI.ModelLike, |
| 93 | + ::MOI.ConstraintFunction, |
| 94 | + bridge::ExponentialConeToScalarNonlinearFunctionBridge, |
| 95 | +) |
| 96 | + return copy(bridge.f) |
| 97 | +end |
| 98 | + |
| 99 | +function MOI.get( |
| 100 | + ::MOI.ModelLike, |
| 101 | + ::MOI.ConstraintSet, |
| 102 | + ::ExponentialConeToScalarNonlinearFunctionBridge, |
| 103 | +) |
| 104 | + return MOI.ExponentialCone() |
| 105 | +end |
| 106 | + |
| 107 | +function MOI.delete( |
| 108 | + model::MOI.ModelLike, |
| 109 | + bridge::ExponentialConeToScalarNonlinearFunctionBridge, |
| 110 | +) |
| 111 | + MOI.delete(model, bridge.ci) |
| 112 | + MOI.delete(model, bridge.ci_y) |
| 113 | + return |
| 114 | +end |
| 115 | + |
| 116 | +function MOI.get( |
| 117 | + ::ExponentialConeToScalarNonlinearFunctionBridge, |
| 118 | + ::MOI.NumberOfVariables, |
| 119 | +)::Int64 |
| 120 | + return 0 |
| 121 | +end |
| 122 | + |
| 123 | +function MOI.get( |
| 124 | + ::ExponentialConeToScalarNonlinearFunctionBridge, |
| 125 | + ::MOI.ListOfVariableIndices, |
| 126 | +)::Vector{MOI.VariableIndex} |
| 127 | + return MOI.VariableIndex[] |
| 128 | +end |
| 129 | + |
| 130 | +function MOI.get( |
| 131 | + bridge::ExponentialConeToScalarNonlinearFunctionBridge{T}, |
| 132 | + ::MOI.NumberOfConstraints{MOI.ScalarNonlinearFunction,MOI.LessThan{T}}, |
| 133 | +)::Int64 where {T} |
| 134 | + return 1 |
| 135 | +end |
| 136 | + |
| 137 | +function MOI.get( |
| 138 | + bridge::ExponentialConeToScalarNonlinearFunctionBridge{T}, |
| 139 | + ::MOI.ListOfConstraintIndices{MOI.ScalarNonlinearFunction,MOI.LessThan{T}}, |
| 140 | +) where {T} |
| 141 | + return [bridge.ci] |
| 142 | +end |
| 143 | + |
| 144 | +function MOI.get( |
| 145 | + bridge::ExponentialConeToScalarNonlinearFunctionBridge{T}, |
| 146 | + ::MOI.NumberOfConstraints{ |
| 147 | + MOI.ScalarAffineFunction{T}, |
| 148 | + MOI.GreaterThan{T}, |
| 149 | + }, |
| 150 | +)::Int64 where {T} |
| 151 | + return 1 |
| 152 | +end |
| 153 | + |
| 154 | +function MOI.get( |
| 155 | + bridge::ExponentialConeToScalarNonlinearFunctionBridge{T}, |
| 156 | + ::MOI.ListOfConstraintIndices{ |
| 157 | + MOI.ScalarAffineFunction{T}, |
| 158 | + MOI.GreaterThan{T}, |
| 159 | + }, |
| 160 | +) where {T} |
| 161 | + return [bridge.ci_y] |
| 162 | +end |
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