[breaking] Modify the dimension of Complements

NEWS.md

@@ -6,7 +6,7 @@ v0.10.0 (In development)
 
 **This is a breaking release.**
 
-Breaking renames: 
+Breaking renames:
 
 - `ListOfConstraints` has been renamed to `ListOfConstraintTypesPresent`
 - `SolveTime` has been renamed to `SolveTimeSec`
@@ -22,6 +22,9 @@ Breaking behavior changes:
 - `CachingOptimizer`s are now initialized as `EMPTY_OPTIMIZER` instead of `ATTACHED_OPTIMIZER`.
   If your code relies on the optimizer being attached, call `MOIU.attach_optimizer(model)`
   after creation.
+- The `dimension` argument to `Complements(dimension::Int)` should now be the
+  length of the corresponding function, instead of half the length. An
+  `ArgumentError` is thrown if `dimension` is not even.
 
 v0.9.21 (April 23, 2021)
 ---------------------------

src/FileFormats/MOF/read.jl

@@ -452,7 +452,7 @@ function set_to_moi(::Val{:DualExponentialCone}, ::Object)
 end
 
 function set_to_moi(::Val{:Complements}, object::Object)
-    return MOI.Complements(div(object["dimension"], 2))
+    return MOI.Complements(object["dimension"])
 end
 
 # ========== Typed vector sets ==========

src/FileFormats/MOF/write.jl

@@ -284,6 +284,7 @@ end
 function head_name(::Type{MOI.PositiveSemidefiniteConeSquare})
     return "PositiveSemidefiniteConeSquare"
 end
+head_name(::Type{MOI.Complements}) = "Complements"
 
 # ========== Typed vector sets ==========
 head_name(::Type{<:MOI.PowerCone}) = "PowerCone"
@@ -302,10 +303,3 @@ function moi_to_object(
         "activate_on" => (I == MOI.ACTIVATE_ON_ONE) ? "one" : "zero",
     )
 end
-
-function moi_to_object(set::MOI.Complements, ::Dict{MOI.VariableIndex,String})
-    return OrderedObject(
-        "type" => "Complements",
-        "dimension" => MOI.dimension(set),
-    )
-end

src/Test/UnitTests/basic_constraint_tests.jl

@@ -123,7 +123,7 @@ const BasicConstraintTests = Dict(
     (MOI.VectorAffineFunction{Float64}, MOI.Nonnegatives) =>
         (dummy_vector_affine, 2, MOI.Nonnegatives(2)),
     (MOI.VectorAffineFunction{Float64}, MOI.Complements) =>
-        (dummy_vector_affine, 2, MOI.Complements(1)),
+        (dummy_vector_affine, 2, MOI.Complements(2)),
     (MOI.VectorAffineFunction{Float64}, MOI.NormInfinityCone) =>
         (dummy_vector_affine, 3, MOI.NormInfinityCone(3)),
     (MOI.VectorAffineFunction{Float64}, MOI.NormOneCone) =>

src/Test/nlp.jl

@@ -527,7 +527,7 @@ function test_linear_mixed_complementarity(
     MOI.add_constraint(
         model,
         MOI.VectorAffineFunction(terms, [q; 0.0; 0.0; 0.0; 0.0]),
-        MOI.Complements(4),
+        MOI.Complements(8),
     )
     @test MOI.get(model, MOI.TerminationStatus()) == MOI.OPTIMIZE_NOT_CALLED
     if config.solve
@@ -631,7 +631,7 @@ function test_qp_complementarity_constraint(
     MOI.add_constraint(
         model,
         MOI.VectorOfVariables([x[3], x[4], x[5], x[6], x[7], x[8]]),
-        MOI.Complements(3),
+        MOI.Complements(6),
     )
     @test MOI.get(model, MOI.TerminationStatus()) == MOI.OPTIMIZE_NOT_CALLED
     if config.solve

src/sets.jl

@@ -806,10 +806,11 @@ The set corresponding to a mixed complementarity constraint.
 Complementarity constraints should be specified with an
 [`AbstractVectorFunction`](@ref)-in-`Complements(dimension)` constraint.
 
-The dimension of the vector-valued function `F` must be `2 * dimension`. This
+The dimension of the vector-valued function `F` must be `dimension`. This
 defines a complementarity constraint between the scalar function `F[i]` and the
-variable in `F[i + dimension]`. Thus, `F[i + dimension]` must be interpretable
-as a single variable `x_i` (e.g., `1.0 * x + 0.0`).
+variable in `F[i + dimension/2]`. Thus, `F[i + dimension/2]` must be
+interpretable as a single variable `x_i` (e.g., `1.0 * x + 0.0`), and
+`dimension` must be even.
 
 The mixed complementarity problem consists of finding `x_i` in the interval
 `[lb, ub]` (i.e., in the set `Interval(lb, ub)`), such that the following holds:
@@ -826,7 +827,7 @@ Classically, the bounding set for `x_i` is `Interval(0, Inf)`, which recovers:
 The problem:
 
     x -in- Interval(-1, 1)
-    [-4 * x - 3, x] -in- Complements(1)
+    [-4 * x - 3, x] -in- Complements(2)
 
 defines the mixed complementarity problem where the following holds:
 
@@ -844,17 +845,27 @@ The function `F` can also be defined in terms of single variables. For example,
 the problem:
 
     [x_3, x_4] -in- Nonnegatives(2)
-    [x_1, x_2, x_3, x_4] -in- Complements(2)
+    [x_1, x_2, x_3, x_4] -in- Complements(4)
 
 defines the complementarity problem where `0 <= x_1 ⟂ x_3 >= 0` and
 `0 <= x_2 ⟂ x_4 >= 0`.
 """
 struct Complements <: AbstractVectorSet
     dimension::Int
+    # Need an explicit Int64 here, because JSON parses Int as Int64, even on
+    # 32-bit machines.
+    function Complements(dimension::Union{Int,Int64})
+        if !iseven(dimension)
+            throw(
+                ArgumentError(
+                    "The dimension of a Complements set must be even.",
+                ),
+            )
+        end
+        return new(convert(Int, dimension))
+    end
 end
 
-dimension(set::Complements) = 2 * set.dimension
-
 # isbits types, nothing to copy
 function Base.copy(
     set::Union{

test/FileFormats/MOF/MOF.jl

@@ -390,7 +390,7 @@ end
     end
     @testset "Complements" begin
         test_model_equality(
-            "variables: x, y\nc1: [x, y] in Complements(1)",
+            "variables: x, y\nc1: [x, y] in Complements(2)",
             ["x", "y"],
             ["c1"],
         )

test/sets.jl

@@ -104,9 +104,11 @@ Base.copy(mlt::MutLessThan) = MutLessThan(Base.copy(mlt.upper))
         @test MOI.dimension(
             MOI.IndicatorSet{MOI.ACTIVATE_ON_ONE}(MOI.LessThan(1.0)),
         ) == 2
-        @test MOI.dimension(MOI.Complements(5)) == 10
+        @test MOI.dimension(MOI.Complements(10)) == 10
+    end
+    @testset "Complements" begin
+        @test_throws ArgumentError MOI.Complements(3)
     end
-
     @testset "Dual Set" begin
         function dual_set_test(set1, set2)
             @test MOI.dual_set(set1) == set2