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Updated user-propagator example (#5879)

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Clemens Eisenhofer 2022-03-03 19:42:06 +01:00 • committed by GitHub
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examples/userPropagator/user_propagator_subquery_maximisation.h Normal file
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#pragma once
#include "user_propagator.h"
class user_propagator_subquery_maximisation : public user_propagator {
z3::expr assertion;
z3::expr_vector queens;
z3::expr manhattanSum;
public:
user_propagator_subquery_maximisation(z3::solver *s, std::unordered_map<z3::expr, unsigned> &idMapping, unsigned board, z3::expr_vector queens)
: user_propagator(s, idMapping, board),
assertion(mk_and(s->assertions())),
queens(queens), manhattanSum(s->ctx().bv_val(0, queens[0].get_sort().bv_size())) {
for (int i = 1; i < queens.size(); i++) {
manhattanSum = manhattanSum + z3::ite(z3::uge(queens[i], queens[i - 1]), queens[i] - queens[i - 1], queens[i - 1] - queens[i]);
}
}
void final() override {
int max1 = 0;
for (unsigned i = 1; i < board; i++) {
max1 += abs((signed) currentModel[i] - (signed) currentModel[i - 1]);
}
z3::expr_vector vec(ctx());
int max2 = 0;
z3::solver subquery(ctx(), z3::solver::simple());
subquery.add(assertion);
subquery.add(z3::ugt(manhattanSum, max1));
if (subquery.check() == z3::unsat)
return; // model is already maximal
z3::model counterExample = subquery.get_model();
int prev, curr = -1;
for (int i = 0; i < queens.size(); i++) {
prev = curr;
curr = counterExample.eval(queens[i]).get_numeral_int();
if (i == 0) continue;
max2 += abs(curr - prev);
}
this->propagate(vec, z3::uge(manhattanSum, max2));
}
};