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instead of building axiom (=> x y), build (or (not x) y)

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this may be a bug in Z3 as it suggests that implications are ignored
e.g. I can assert the axiom (=> true false) and Z3 is okay with this
This commit is contained in:
Murphy Berzish 2015-09-28 03:20:13 -04:00
parent 5fe129b571
commit bccadedfee
2 changed files with 16 additions and 8 deletions
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23
src/smt/theory_str.cpp
View file

@ -39,7 +39,9 @@ void theory_str::assert_axiom(ast * a) {
if (get_manager().is_true(e)) return;
TRACE("t_str_detail", tout << "asserting " << mk_ismt2_pp(a, get_manager()) << "\n";);
context & ctx = get_context();
ctx.internalize(e, false);
if (!ctx.b_internalized(e)) {
ctx.internalize(e, true);
}
literal lit(ctx.get_literal(e));
ctx.mark_as_relevant(lit);
ctx.mk_th_axiom(get_id(), 1, &lit);
@ -372,14 +374,15 @@ void theory_str::solve_concat_eq_str(expr * concat, expr * str) {
TRACE("t_str", tout << "quick path: concat == \"\"" << std::endl;);
// assert the following axiom:
// ( (Concat a1 a2) == "" ) -> ( (a1 == "") AND (a2 == "") )
expr_ref empty_str(m_strutil.mk_string(""), m);
expr_ref premise(ctx.mk_eq_atom(concat, empty_str), m);
expr_ref c1(ctx.mk_eq_atom(a1, empty_str), m);
expr_ref c2(ctx.mk_eq_atom(a2, empty_str), m);
expr_ref premise(ctx.mk_eq_atom(concat, str), m);
expr_ref c1(ctx.mk_eq_atom(a1, str), m);
expr_ref c2(ctx.mk_eq_atom(a2, str), m);
expr_ref conclusion(m.mk_and(c1, c2), m);
expr_ref axiom(m.mk_implies(premise, conclusion), m);
TRACE("t_str_detail", tout << "learn " << mk_ismt2_pp(axiom, m) << std::endl;);
expr_ref axiom(m.mk_or(m.mk_not(premise), conclusion), m);
assert_axiom(axiom);
return;
}
// TODO the rest...
@ -561,7 +564,7 @@ void theory_str::init_search_eh() {
/*
* Similar recursive descent, except over all initially assigned terms.
* This is done to find equalities between terms, etc. that we otherwise
* wouldn't get a chance to see.
* might not get a chance to see.
*/
expr_ref_vector assignments(m);
ctx.get_assignments(assignments);
@ -615,6 +618,10 @@ void theory_str::push_scope_eh() {
TRACE("t_str", tout << "push" << std::endl;);
}
void theory_str::pop_scope_eh(unsigned num_scopes) {
TRACE("t_str", tout << "pop " << num_scopes << std::endl;);
}
final_check_status theory_str::final_check_eh() {
ast_manager & m = get_manager();
context & ctx = get_context();

1
src/smt/theory_str.h
View file

@ -93,6 +93,7 @@ namespace smt {
virtual void relevant_eh(app * n);
virtual void assign_eh(bool_var v, bool is_true);
virtual void push_scope_eh();
virtual void pop_scope_eh(unsigned num_scopes);
virtual void reset_eh();
virtual bool can_propagate();