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fixes to #596 and #592: use exponential step increments on integer problems, align int.to.str with canonizer and disequality checker

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-05-17 01:00:42 -07:00
parent 5250c3b9ed
commit ec565ae7a0
6 changed files with 289 additions and 55 deletions
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77
src/smt/theory_seq.cpp
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@ -1820,16 +1820,23 @@ bool theory_seq::solve_ne(unsigned idx) {
TRACE("seq", display_disequation(tout << "reduces to false: ", n););
return true;
}
else if (!change) {
TRACE("seq", tout << "no change " << n.ls(i) << " " << n.rs(i) << "\n";);
if (updated) {
new_ls.push_back(n.ls(i));
new_rs.push_back(n.rs(i));
}
continue;
}
else {
// eliminate ite expressions.
reduce_ite(lhs, new_lits, num_undef_lits, change);
reduce_ite(rhs, new_lits, num_undef_lits, change);
reduce_ite(ls, new_lits, num_undef_lits, change);
reduce_ite(rs, new_lits, num_undef_lits, change);
if (!change) {
TRACE("seq", tout << "no change " << n.ls(i) << " " << n.rs(i) << "\n";);
if (updated) {
new_ls.push_back(n.ls(i));
new_rs.push_back(n.rs(i));
}
continue;
}
if (!updated) {
for (unsigned j = 0; j < i; ++j) {
new_ls.push_back(n.ls(j));
@ -1933,6 +1940,33 @@ bool theory_seq::solve_ne(unsigned idx) {
return updated;
}
void theory_seq::reduce_ite(expr_ref_vector & ls, literal_vector& new_lits, unsigned& num_undef_lits, bool& change) {
expr* cond, *th, *el;
context& ctx = get_context();
for (unsigned i = 0; i < ls.size(); ++i) {
expr* e = ls[i].get();
if (m.is_ite(e, cond, th, el)) {
literal lit(mk_literal(cond));
switch (ctx.get_assignment(lit)) {
case l_true:
change = true;
new_lits.push_back(lit);
ls[i] = th;
break;
case l_false:
change = true;
new_lits.push_back(~lit);
ls[i] = el;
break;
case l_undef:
++num_undef_lits;
break;
}
}
}
}
bool theory_seq::solve_nc(unsigned idx) {
nc const& n = m_ncs[idx];
@ -2212,7 +2246,6 @@ bool theory_seq::add_itos_axiom(expr* e) {
if (get_value(n, val)) {
if (!m_itos_axioms.contains(val)) {
m_itos_axioms.insert(val);
app_ref e1(m_util.str.mk_string(symbol(val.to_string().c_str())), m);
expr_ref n1(arith_util(m).mk_numeral(val, true), m);
add_axiom(mk_eq(m_util.str.mk_itos(n1), e1, false));
@ -2604,6 +2637,32 @@ expr_ref theory_seq::expand(expr* e0, dependency*& eqs) {
else if (m_util.str.is_index(e, e1, e2, e3)) {
result = m_util.str.mk_index(expand(e1, deps), expand(e2, deps), e3);
}
else if (m_util.str.is_itos(e, e1)) {
rational val;
if (get_value(e1, val)) {
expr_ref num(m), res(m);
context& ctx = get_context();
num = m_autil.mk_numeral(val, true);
if (!ctx.e_internalized(num)) {
ctx.internalize(num, false);
}
enode* n1 = ctx.get_enode(num);
enode* n2 = ctx.get_enode(e1);
res = m_util.str.mk_string(symbol(val.to_string().c_str()));
if (n1->get_root() == n2->get_root()) {
result = res;
deps = m_dm.mk_join(deps, m_dm.mk_leaf(assumption(n1, n2)));
}
else {
add_axiom(~mk_eq(num, e1, false), mk_eq(e, res, false));
add_axiom(mk_eq(num, e1, false), ~mk_eq(e, res, false));
result = e;
}
}
else {
result = e;
}
}
else {
result = e;
}