check if inner violated and not just fixed (#266)

* check if inner violated and not just fixed
* changed! functionality to avoid recomputation of recompute_lc_extrema
* call changed directly before prune
* v0.6.9

Author: Wikunia

CHANGELOG.md

@@ -1,5 +1,8 @@
 # ConstrainSolver.jl - Changelog
 
+## v0.6.9 (17th of July 2021)
+- set activator to false when inner violated [PR #266](https://github.com/Wikunia/ConstraintSolver.jl/pull/266)
+
 ## v0.6.8 (14th of June 2021)
 - support for xor and xnor constraints 
 - better bridge structure for boolean constraints

Project.toml

@@ -1,7 +1,7 @@
 name = "ConstraintSolver"
 uuid = "e0e52ebd-5523-408d-9ca3-7641f1cd1405"
 authors = ["Ole Kröger <[email protected]>"]
-version = "0.6.8"
+version = "0.6.9"
 
 [deps]
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"

src/constraints/boolset.jl

@@ -298,3 +298,11 @@ function finished_pruning_constraint!(
         end
     end
 end
+
+
+function changed!(com::CS.CoM, constraint::BoolConstraint, fct, set)
+    lhs = constraint.lhs
+    changed!(com, lhs, lhs.fct, lhs.set)
+    rhs = constraint.rhs
+    changed!(com, rhs, rhs.fct, rhs.set)
+end

src/constraints/indicator.jl

@@ -229,4 +229,9 @@ function is_constraint_violated(
         )
     end
     return false
+end
+
+function changed!(com::CS.CoM, constraint::IndicatorConstraint, fct, set)
+    inner_constraint = constraint.inner_constraint
+    changed!(com, inner_constraint, inner_constraint.fct, inner_constraint.set)
 end

src/constraints/linear_constraints.jl

@@ -82,7 +82,7 @@ function init_constraint!(
     constraint.strict_rhs = set.set.upper - fct.constant
     constraint.is_strict = true
     is_no_variable_constraint(constraint) && return fct.constant < set.set.upper
-
+    recompute_lc_extrema!(com, constraint, fct)
     return true
 end
 
@@ -100,6 +100,7 @@ function init_constraint!(
 ) where {T<:Real}
     constraint.rhs = set.upper - fct.constant
     is_no_variable_constraint(constraint) && return fct.constant <= set.upper
+    recompute_lc_extrema!(com, constraint, fct)
     return true
 end
 
@@ -111,9 +112,14 @@ function init_constraint!(
 ) where {T<:Real}
     constraint.rhs = set.value - fct.constant
     is_no_variable_constraint(constraint) && return fct.constant == set.value
+    recompute_lc_extrema!(com, constraint, fct)
     return true
 end
 
+function changed!(com::CS.CoM, constraint::LinearConstraint, fct, set)
+    recompute_lc_extrema!(com, constraint, fct)
+end
+
 """
     get_new_extrema_and_sum(search_space, vidx, i, terms, full_min, full_max, pre_mins, pre_maxs)
 
@@ -232,8 +238,7 @@ function prune_constraint!(
     search_space = com.search_space
     rhs = constraint.rhs
 
-    # compute max and min values for each index
-    recompute_lc_extrema!(com, constraint, fct)
+    # reuse calculated max and min values for each index
     maxs = constraint.maxs
     mins = constraint.mins
     pre_maxs = constraint.pre_maxs
@@ -530,7 +535,6 @@ function is_constraint_solved(
     fct::SAF{T},
     set::MOI.LessThan{T},
 ) where T
-    recompute_lc_extrema!(com, constraint, fct)
     sum_maxs = sum(constraint.maxs)
     return sum_maxs <= MOI.constant(set)
 end
@@ -551,7 +555,6 @@ function is_constraint_solved(
     fct::SAF{T},
     set::Strictly{T, MOI.LessThan{T}},
 ) where T
-    recompute_lc_extrema!(com, constraint, fct)
     sum_maxs = sum(constraint.maxs)
     return sum_maxs < MOI.constant(set)
 end
@@ -611,7 +614,6 @@ function is_constraint_violated(
         )
     end
     # check if it can be feasible using the minimum sum
-    recompute_lc_extrema!(com, constraint, fct)
     return !min_sum_feasible(com, sum(constraint.mins), set)
 end
 
@@ -629,4 +631,14 @@ function min_sum_feasible(com, min_sum, set::Strictly{T, MOI.LessThan{T}}) where
         return get_approx_discrete(min_sum) < get_approx_discrete(MOI.constant(set))
     end
     return min_sum <= MOI.constant(set) + com.options.atol
+end
+
+function reverse_pruning_constraint!(
+    com::CoM,
+    constraint::LinearConstraint,
+    fct::SAF{T},
+    set::Union{MOI.LessThan, MOI.EqualTo, Strictly{T, MOI.LessThan{T}}},
+    backtrack_id::Int,
+) where {T <: Real}
+    recompute_lc_extrema!(com, constraint, fct)
 end

src/constraints/reified.jl

@@ -50,7 +50,7 @@ function prune_constraint!(
     logs = true,
 ) where {A,T<:Real,RS<:ReifiedSet{A}}
     # 1. if the inner constraint is solved then the reified variable can be set to activate_on
-    # 2. if the complement of the inner constraint is solved (all fixed but don't fulfill) the reified variable can be set to !activate_on
+    # 2. if the inner constraint is infeasible the reified variable can be set to !activate_on
     # 3. if the reified constraint is active then prune can be called for the inner constraint
     # 4. if the reified constraint is fixed to inactive one can complement prune
 
@@ -61,26 +61,17 @@ function prune_constraint!(
     activate_on = Int(constraint.activate_on)
     activate_off = activate_on == 1 ? 0 : 1
 
-    # 1
-    if is_constraint_solved(
-        com,
-        inner_constraint,
-        inner_constraint.fct,
-        inner_constraint.set,
-    )
-        !fix!(com, variables[rei_vidx], activate_on) && return false
-        # 2
-    elseif all(isfixed(variables[vidx]) for vidx in inner_constraint.indices)
-        !fix!(com, variables[rei_vidx], activate_off) && return false
-        # 3
-    elseif issetto(variables[rei_vidx], activate_on)
+
+    # 3
+    if issetto(variables[rei_vidx], activate_on)
         !activate_inner!(com, constraint) && return false
         return prune_constraint!(
             com,
             inner_constraint,
             inner_constraint.fct,
             inner_constraint.set,
         )
+    # 4
     elseif issetto(variables[rei_vidx], activate_off) && complement_constraint !== nothing
         !activate_complement_inner!(com, constraint) && return false
         return prune_constraint!(
@@ -89,6 +80,22 @@ function prune_constraint!(
             complement_constraint.fct,
             complement_constraint.set,
         )
+    # 1
+    elseif is_constraint_solved(
+        com,
+        inner_constraint,
+        inner_constraint.fct,
+        inner_constraint.set,
+    )
+        !fix!(com, variables[rei_vidx], activate_on) && return false
+    # 2
+    elseif is_constraint_violated(
+        com,
+        inner_constraint,
+        inner_constraint.fct,
+        inner_constraint.set,
+    )
+        !fix!(com, variables[rei_vidx], activate_off) && return false
     end
     return true
 end
@@ -199,3 +206,12 @@ function is_constraint_violated(
     end
     return false
 end
+
+function changed!(com::CS.CoM, constraint::ReifiedConstraint, fct, set)
+    inner_constraint = constraint.inner_constraint
+    changed!(com, inner_constraint, inner_constraint.fct, inner_constraint.set)
+    if constraint.complement_constraint !== nothing
+        complement_constraint = constraint.complement_constraint 
+        changed!(com, complement_constraint, complement_constraint.fct, complement_constraint.set)
+    end
+end

src/pruning.jl

@@ -78,8 +78,6 @@ function prune!(
 
     # while we haven't called every constraint
     while true
-        b_open_constraint = false
-        # will be changed or b_open_constraint => false
         open_pos, ci = get_next_prune_constraint(com, constraint_idxs_vec)
         # no open values => don't need to call again
         if open_pos == 0 && !initial_check
@@ -93,6 +91,7 @@ function prune!(
         constraint_idxs_vec[ci] = N
         constraint = com.constraints[ci]
 
+        changed!(com, constraint, constraint.fct, constraint.set)
         feasible =
             prune_constraint!(com, constraint, constraint.fct, constraint.set; logs = false)
         if !pre_backtrack
@@ -118,11 +117,11 @@ function prune!(
                         inner_constraint = com.constraints[ci]
                         # if initial check or don't add constraints => update only those which already have open possibilities
                         if (only_once || initial_check) &&
-                           constraint_idxs_vec[inner_constraint.idx] == N
+                            constraint_idxs_vec[inner_constraint.idx] == N
                             continue
                         end
                         constraint_idxs_vec[inner_constraint.idx] =
-                            open_possibilities(search_space, inner_constraint.indices)
+                        open_possibilities(search_space, inner_constraint.indices)
                     end
                 end
             end

src/util.jl

@@ -370,4 +370,8 @@ function view_changes(v::Variable, step_nr::Int)
     idx_begin = v.changes.indices[step_nr]
     idx_end = v.changes.indices[step_nr+1]-1
     return @views v.changes.changes[idx_begin:idx_end]
+end
+
+function changed!(com::CS.CoM, constraint::Constraint, fct, set)
+    return 
 end

test/unit/constraints/and.jl

@@ -162,6 +162,7 @@ end
 
     constr_indices = constraint.indices
     @test CS.fix!(com, variables[constraint.indices[3]], 0; check_feasibility = false)
+    CS.changed!(com, constraint, constraint.fct, constraint.set)
     @test !CS.prune_constraint!(com, constraint, constraint.fct, constraint.set)
 end
 

test/unit/constraints/complement.jl

@@ -9,6 +9,7 @@
     constraint = com.constraints[1]
     @test CS.fix!(com, variables[constraint.indices[1]], 1; check_feasibility = false)
     @test CS.fix!(com, variables[constraint.indices[2]], 2; check_feasibility = false)
+    CS.changed!(com, constraint, constraint.fct, constraint.set)
     @test CS.is_constraint_solved(com, constraint, constraint.fct, constraint.set)
 
     #################
@@ -23,6 +24,7 @@
     constraint = com.constraints[1]
     @test CS.fix!(com, variables[constraint.indices[1]], 1; check_feasibility = false)
     @test CS.fix!(com, variables[constraint.indices[2]], 1; check_feasibility = false)
+    CS.changed!(com, constraint, constraint.fct, constraint.set)
     @test CS.is_constraint_solved(com, constraint, constraint.fct, constraint.set)
 
     #################
@@ -39,6 +41,7 @@
     xor_constraint = com.constraints[1].inner_constraint
     @test CS.fix!(com, variables[xor_constraint.indices[1]], 0; check_feasibility = false)
     @test CS.fix!(com, variables[xor_constraint.indices[2]], 2; check_feasibility = false)
+    CS.changed!(com, xor_constraint, xor_constraint.fct, xor_constraint.set)
     @test CS.is_constraint_solved(com, xor_constraint, xor_constraint.fct, xor_constraint.set)
 
     #################
@@ -55,6 +58,7 @@
     xor_constraint = com.constraints[1].inner_constraint
     @test CS.fix!(com, variables[xor_constraint.indices[1]], 0; check_feasibility = false)
     @test CS.fix!(com, variables[xor_constraint.indices[2]], 2; check_feasibility = false)
+    CS.changed!(com, xor_constraint, xor_constraint.fct, xor_constraint.set)
     @test CS.is_constraint_solved(com, xor_constraint, xor_constraint.fct, xor_constraint.set)