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update handling for set membership

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2025-11-24 03:57:01 -08:00
parent 7bc592749d
commit 7d2c84465c
2 changed files with 23 additions and 39 deletions
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61
src/smt/theory_finite_set_size.cpp
View file

@ -73,11 +73,13 @@ namespace smt {
TRACE(finite_set, tout << "assoc " << name << " to " << enode_pp(n, ctx) << " " << enode_pp(n->get_root(), ctx) << "\n";);
}
add_def_axioms(ns);
add_singleton_axioms(ns); // (set.in x s) -> |{x}| = 1
add_diseq_axioms(ns); // |x\y| > 0 or |y\x| > 0
add_not_in_axioms(ns); // not (x in s) -> |{x}\s| = 1
add_eq_axioms(ns);
add_def_axioms(ns);
// b_{s u t} <-> b_{s} or b_{t},
// b_{s n t} <-> b_{s} and b_{t},
// b_{s\t} <-> b_{s} and not b_{t}
add_singleton_axioms(ns); // (set.in x s) -> b_{x} => b_s - for occurrences of (set.in x s)
add_diseq_axioms(ns); // s = t or |s\t| > 0 or |t\s| > 0 - for disqualities
add_eq_axioms(ns); // s = t -> b_{s} <=> b_{t} - for equalities
TRACE(finite_set, display(tout));
}
@ -121,7 +123,12 @@ namespace smt {
}
/**
* For every set membership (set.in x s) add axiom for (set.subset (set.singleton x) s)
* For every set membership (set.in x s) track propositional
* (set.in x S) => b_{x} => b_S
* ~(set.in x S) => b_{x} => not b_S
*
* Constrain singletons with cardinality constraints:
* |{x}| = 1
*/
void theory_finite_set_size::add_singleton_axioms(enode_vector const &ns) {
@ -132,7 +139,7 @@ namespace smt {
if (!ctx.is_relevant(p))
continue;
auto v = ctx.get_assignment(p);
if (v != l_true)
if (v == l_undef)
continue;
auto e = p->get_arg(0)->get_root();
TRACE(finite_set, tout << "singleton axiom for " << enode_pp(e, ctx) << " in " << enode_pp(p, ctx)
@ -140,39 +147,24 @@ namespace smt {
auto s = mk_singleton(e);
SASSERT(n2b.contains(p->get_arg(1)));
SASSERT(n2b.contains(s));
auto is_in = m.mk_implies(n2b[s], n2b[p->get_arg(1)]);
auto X = n2b[s];
auto S = n2b[p->get_arg(1)];
if (v == l_false)
S = m.mk_not(S);
auto is_in = m.mk_implies(X, S);
in lit(p, v == l_true);
std::ostringstream strm;
strm << "|" << enode_pp(p, ctx) << "|";
strm << "|" << (v == l_false ? "~":"") << enode_pp(p, ctx) << "|";
symbol name = symbol(strm.str());
expr* t = m.mk_const(name, m.mk_bool_sort());
bs.push_back(t);
m_assumptions.insert(t, lit);
m_solver->assert_expr(m.mk_implies(t, is_in));
}
}
}
/*
* For every x not in S include the assertion
* x in S or |{x} \ S| = 1
*/
void theory_finite_set_size::add_not_in_axioms(enode_vector const &ns) {
for (auto n : ns) {
for (auto p : enode::parents(n)) {
if (!u.is_in(p->get_expr()))
continue;
auto v = ctx.get_assignment(p);
if (v != l_false)
continue;
// add size axiom |s| = 1
arith_util a(m);
auto x = p->get_arg(0);
auto S = p->get_arg(1);
auto X = mk_singleton(x);
auto X_minus_S = mk_diff(X, S);
auto l1 = th.mk_literal(p->get_expr());
auto l2 = th.mk_literal(m.mk_eq(u.mk_size(X_minus_S->get_expr()), a.mk_int(1)));
ctx.mk_th_axiom(th.get_id(), l1, l2);
auto l = th.mk_literal(m.mk_eq(u.mk_size(s->get_expr()), a.mk_int(1)));
ctx.mk_th_axiom(th.get_id(), l);
}
}
}
@ -220,8 +212,6 @@ namespace smt {
}
}
/**
* Walk the cone of influence of expresions that depend on ns
*/
@ -292,15 +282,10 @@ namespace smt {
continue;
if (!ctx.is_relevant(p))
continue;
if (ctx.get_assignment(p) != l_false)
continue;
auto x = p->get_arg(0)->get_root();
auto X = mk_singleton(x);
ctx.mark_as_relevant(X->get_expr());
add_expression(X);
auto D = mk_diff(X, p->get_arg(1));
ctx.mark_as_relevant(D);
add_expression(D);
}
}
for (auto n : ns)

1
src/smt/theory_finite_set_size.h
View file

@ -56,7 +56,6 @@ namespace smt {
void add_singleton_axioms(enode_vector const &ns);
void add_eq_axioms(enode_vector const &ns);
void add_diseq_axioms(enode_vector const &ns);
void add_not_in_axioms(enode_vector const &ns);
enode *mk_singleton(enode* n);
enode *mk_diff(enode *a, enode *b);
void initialize_solver();