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fix bugs exposed in #677. to_int(x) has the semantics that to_int(x) <= x, and to_int(x) is the largest integer satisfying this inequality. The encoding in purify_arith had it the other way x <= to_int(x) contrary to how to_int(x) is handled elsewhere. Another bug in theory_arith for mixed-integer linear case was also exposed. Fractional bounds on expressions of the form to_int(x), and more generally on integer rows were not rounded prior to internalization

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2016-07-13 20:32:18 -07:00
parent 63f89f8c45
commit 3989d238c0
8 changed files with 78 additions and 40 deletions
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9
src/tactic/arith/purify_arith_tactic.cpp
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@ -378,12 +378,13 @@ struct purify_arith_proc {
cache_result(t, result, result_pr);
expr * x = args[0];
// to-real(k) - x >= 0
expr * diff = u().mk_add(u().mk_to_real(k), u().mk_mul(u().mk_numeral(rational(-1), false), x));
// x - to-real(k) >= 0
expr * diff = u().mk_add(x, u().mk_mul(u().mk_numeral(rational(-1), false), u().mk_to_real(k)));
push_cnstr(u().mk_ge(diff, mk_real_zero()));
push_cnstr_pr(result_pr);
// not(to-real(k) - x >= 1)
// not(x - to-real(k) >= 1)
push_cnstr(NOT(u().mk_ge(diff, u().mk_numeral(rational(1), false))));
push_cnstr_pr(result_pr);
}
@ -757,6 +758,7 @@ struct purify_arith_proc {
// add cnstraints
sz = r.cfg().m_new_cnstrs.size();
TRACE("purify_arith", tout << r.cfg().m_new_cnstrs << "\n";);
for (unsigned i = 0; i < sz; i++) {
m_goal.assert_expr(r.cfg().m_new_cnstrs.get(i), m_produce_proofs ? r.cfg().m_new_cnstr_prs.get(i) : 0, 0);
}
@ -827,6 +829,7 @@ public:
SASSERT(g->is_well_sorted());
mc = 0; pc = 0; core = 0;
tactic_report report("purify-arith", *g);
TRACE("purify_arith", g->display(tout););
bool produce_proofs = g->proofs_enabled();
bool produce_models = g->models_enabled();
bool elim_root_objs = m_params.get_bool("elim_root_objects", true);