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working on pdr

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2012-10-14 00:24:17 -07:00
parent 16cfb3895d
commit 990b93c2fd
6 changed files with 64 additions and 50 deletions
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22
lib/pdr_context.cpp
View file

@ -914,7 +914,7 @@ namespace pdr {
}
obj_map<expr, unsigned>& model_search::cache(model_node const& n) {
unsigned l = n.level();
unsigned l = n.orig_level();
if (l >= m_cache.size()) {
m_cache.resize(l + 1);
}
@ -1108,6 +1108,21 @@ namespace pdr {
}
}
void model_search::backtrack_level(bool uses_level, model_node& n) {
SASSERT(m_root);
if (uses_level && m_root->level() > n.level()) {
IF_VERBOSE(2, verbose_stream() << "Increase level " << n.level() << "\n";);
n.increase_level();
m_leaves.push_back(&n);
}
else {
model_node* p = n.parent();
if (p) {
set_leaf(*p);
}
}
}
// ----------------
// context
@ -1604,10 +1619,7 @@ namespace pdr {
TRACE("pdr", tout << "invariant state: " << (uses_level?"":"(inductive) ") << mk_pp(ncube, m) << "\n";);
n.pt().add_property(ncube, uses_level?n.level():infty_level);
CASSERT("pdr",n.level() == 0 || check_invariant(n.level()-1));
model_node* p = n.parent();
if (p) {
m_search.set_leaf(*p);
}
m_search.backtrack_level(uses_level && m_params.get_bool(":flexible-trace",true), n);
break;
}
case l_undef: {

7
lib/pdr_context.h
View file

@ -171,10 +171,11 @@ namespace pdr {
model_ref m_model;
ptr_vector<model_node> m_children;
unsigned m_level;
unsigned m_orig_level;
bool m_closed;
public:
model_node(model_node* parent, expr_ref& state, pred_transformer& pt, unsigned level):
m_parent(parent), m_pt(pt), m_state(state), m_model(0), m_level(level), m_closed(false) {
m_parent(parent), m_pt(pt), m_state(state), m_model(0), m_level(level), m_orig_level(level), m_closed(false) {
if (m_parent) {
m_parent->m_children.push_back(this);
SASSERT(m_parent->m_level == level+1);
@ -183,6 +184,8 @@ namespace pdr {
}
void set_model(model_ref& m) { m_model = m; }
unsigned level() const { return m_level; }
unsigned orig_level() const { return m_orig_level; }
void increase_level() { ++m_level; }
expr* state() const { return m_state; }
ptr_vector<model_node> const& children() { return m_children; }
pred_transformer& pt() const { return m_pt; }
@ -245,6 +248,8 @@ namespace pdr {
expr_ref get_trace() const;
proof_ref get_proof_trace(context const& ctx) const;
void backtrack_level(bool uses_level, model_node& n);
};
struct model_exception { };

40
lib/pdr_dl_interface.cpp
View file

@ -184,35 +184,23 @@ void dl_interface::updt_params() {
void dl_interface::collect_params(param_descrs& p) {
p.insert(":bfs-model-search", CPK_BOOL, "PDR: (default true) use BFS strategy for expanding model search");
p.insert(":use-farkas", CPK_BOOL, "PDR: (default true) use lemma generator based on Farkas (for linear real arithmetic)");
p.insert(":generate-proof-trace", CPK_BOOL, "PDR: (default false) trace for 'sat' answer as proof object");
p.insert(":inline-proofs", CPK_BOOL, "PDR: (default true) run PDR with proof mode turned on and extract Farkas coefficients directly (instead of creating a separate proof object when extracting coefficients)");
p.insert(":flexible-trace", CPK_BOOL, "PDR: (default true) allow PDR generate long counter-examples by extending candidate trace within search area");
PRIVATE_PARAMS(p.insert(":use-farkas-model", CPK_BOOL, "PDR: (default false) enable using Farkas generalization through model propagation"););
PRIVATE_PARAMS(p.insert(":use-precondition-generalizer", CPK_BOOL, "PDR: (default false) enable generalizations from weakest pre-conditions"););
PRIVATE_PARAMS(p.insert(":use-multicore-generalizer", CPK_BOOL,
"PDR: (default false) extract multiple cores for blocking states"););
PRIVATE_PARAMS(p.insert(":use-farkas-properties", CPK_BOOL,
"PDR: (default false) experimental Farkas lemma generation method"););
PRIVATE_PARAMS(p.insert(":use-inductive-generalizer", CPK_BOOL,
"PDR: (default true) generalize lemmas using induction strengthening"););
PRIVATE_PARAMS(p.insert(":use-interpolants", CPK_BOOL,
"PDR: (default false) use iZ3 interpolation for lemma generation"););
PRIVATE_PARAMS(p.insert(":dump-interpolants", CPK_BOOL,
"PDR: (default false) display interpolants"););
p.insert(":cache-mode", CPK_UINT, "PDR: use no (0 - default) symbolic (1) or explicit cache (2) for model search");
PRIVATE_PARAMS(p.insert(":use-multicore-generalizer", CPK_BOOL, "PDR: (default false) extract multiple cores for blocking states"););
PRIVATE_PARAMS(p.insert(":use-farkas-properties", CPK_BOOL, "PDR: (default false) experimental Farkas lemma generation method"););
PRIVATE_PARAMS(p.insert(":use-inductive-generalizer", CPK_BOOL, "PDR: (default true) generalize lemmas using induction strengthening"););
PRIVATE_PARAMS(p.insert(":use-interpolants", CPK_BOOL, "PDR: (default false) use iZ3 interpolation for lemma generation"););
PRIVATE_PARAMS(p.insert(":dump-interpolants", CPK_BOOL, "PDR: (default false) display interpolants"););
PRIVATE_PARAMS(p.insert(":cache-mode", CPK_UINT, "PDR: use no (0 - default) symbolic (1) or explicit cache (2) for model search"););
PRIVATE_PARAMS(p.insert(":inductive-reachability-check", CPK_BOOL,
"PDR: (default false) assume negation of the cube on the previous level when "
"checking for reachability (not only during cube weakening)"););
PRIVATE_PARAMS(p.insert(":max-num-contexts", CPK_UINT,
"PDR: (default 500) maximal number of contexts to create"););
PRIVATE_PARAMS(p.insert(":try-minimize-core", CPK_BOOL,
"PDR: (default false) try to reduce core size (before inductive minimization)"););
PRIVATE_PARAMS(p.insert(":simplify-formulas-pre", CPK_BOOL,
"PDR: (default false) simplify derived formulas before inductive propagation"););
PRIVATE_PARAMS(p.insert(":simplify-formulas-post", CPK_BOOL,
"PDR: (default false) simplify derived formulas after inductive propagation"););
PRIVATE_PARAMS(p.insert(":slice", CPK_BOOL,
"PDR: (default true) simplify clause set using slicing"););
p.insert(":generate-proof-trace", CPK_BOOL,
"PDR: (default false) trace for 'sat' answer as proof object");
p.insert(":inline-proofs", CPK_BOOL, "PDR: (default true) run PDR with proof mode turned on and extract Farkas coefficients directly (instead of creating a separate proof object when extracting coefficients)");
PRIVATE_PARAMS(p.insert(":max-num-contexts", CPK_UINT, "PDR: (default 500) maximal number of contexts to create"););
PRIVATE_PARAMS(p.insert(":try-minimize-core", CPK_BOOL, "PDR: (default false) try to reduce core size (before inductive minimization)"););
PRIVATE_PARAMS(p.insert(":simplify-formulas-pre", CPK_BOOL, "PDR: (default false) simplify derived formulas before inductive propagation"););
PRIVATE_PARAMS(p.insert(":simplify-formulas-post", CPK_BOOL, "PDR: (default false) simplify derived formulas after inductive propagation"););
PRIVATE_PARAMS(p.insert(":slice", CPK_BOOL, "PDR: (default true) simplify clause set using slicing"););
}

36
lib/pdr_farkas_learner.cpp
View file

@ -227,8 +227,7 @@ namespace pdr {
: m_proof_params(get_proof_params(params)),
m_pr(PROOF_MODE),
p2o(m_pr, outer_mgr),
o2p(outer_mgr, m_pr),
m_simplifier(mk_arith_bounds_tactic(outer_mgr))
o2p(outer_mgr, m_pr)
{
m_pr.register_decl_plugins();
m_ctx = alloc(smt::solver, m_pr, m_proof_params);
@ -322,7 +321,6 @@ namespace pdr {
for (unsigned i = 0; i < ilemmas.size(); ++i) {
lemmas.push_back(p2o(ilemmas[i].get()));
}
simplify_lemmas(lemmas);
}
m_ctx->pop(1);
@ -358,10 +356,11 @@ namespace pdr {
// Perform simple subsumption check of lemmas.
//
void farkas_learner::simplify_lemmas(expr_ref_vector& lemmas) {
goal_ref g(alloc(goal, lemmas.get_manager(), false, false, false));
ast_manager& m = lemmas.get_manager();
goal_ref g(alloc(goal, m, false, false, false));
TRACE("farkas_simplify_lemmas",
for (unsigned i = 0; i < lemmas.size(); ++i) {
tout << mk_pp(lemmas[i].get(), lemmas.get_manager()) << "\n";
tout << mk_pp(lemmas[i].get(), m) << "\n";
});
for (unsigned i = 0; i < lemmas.size(); ++i) {
@ -369,9 +368,10 @@ namespace pdr {
}
model_converter_ref mc;
proof_converter_ref pc;
expr_dependency_ref core(lemmas.get_manager());
expr_dependency_ref core(m);
goal_ref_buffer result;
(*m_simplifier)(g, result, mc, pc, core);
tactic_ref simplifier = mk_arith_bounds_tactic(m);
(*simplifier)(g, result, mc, pc, core);
lemmas.reset();
SASSERT(result.size() == 1);
goal* r = result[0];
@ -502,6 +502,9 @@ namespace pdr {
units under Farkas.
*/
#define INSERT(_x_) if (!lemma_set.contains(_x_)) { lemma_set.insert(_x_); lemmas.push_back(_x_); }
void farkas_learner::get_lemmas(proof* root, expr_set const& bs, expr_ref_vector& lemmas) {
ast_manager& m = lemmas.get_manager();
bool_rewriter brwr(m);
@ -514,11 +517,12 @@ namespace pdr {
proof_ref pr(root, m);
proof_utils::reduce_hypotheses(pr);
IF_VERBOSE(3, verbose_stream() << "Elim Hyps:\n" << mk_ismt2_pp(pr, m) << "\n";);
proof_utils::permute_unit_resolution(pr);
IF_VERBOSE(3, verbose_stream() << "Reduced proof:\n" << mk_ismt2_pp(pr, m) << "\n";);
ptr_vector<expr_set> hyprefs;
obj_map<expr, expr_set*> hypmap;
obj_hashtable<expr> lemma_set;
ast_mark b_depend, a_depend, visited, b_closed;
expr_set* empty_set = alloc(expr_set);
hyprefs.push_back(empty_set);
@ -574,21 +578,23 @@ namespace pdr {
#define IS_B_PURE(_p) (b_depend.is_marked(_p) && !a_depend.is_marked(_p) && hypmap.find(_p)->empty())
// Add lemmas that depend on bs, have no hypotheses, don't depend on A.
if ((!hyps->empty() || a_depend.is_marked(p)) &&
b_depend.is_marked(p) && !is_farkas_lemma(m, p)) {
for (unsigned i = 0; i < m.get_num_parents(p); ++i) {
app* arg = to_app(p->get_arg(i));
if (IS_B_PURE(arg)) {
if (is_pure_expr(Bsymbs, m.get_fact(arg))) {
expr* fact = m.get_fact(arg);
if (is_pure_expr(Bsymbs, fact)) {
TRACE("farkas_learner",
tout << "Add: " << mk_pp(m.get_fact(arg), m) << "\n";
tout << mk_pp(arg, m) << "\n";
);
lemmas.push_back(m.get_fact(arg));
INSERT(fact);
}
else {
get_asserted(p, bs, b_closed, lemmas);
get_asserted(p, bs, b_closed, lemma_set, lemmas);
b_closed.mark(p, true);
}
}
@ -707,7 +713,7 @@ namespace pdr {
expr_ref res(m);
combine_constraints(coeffs.size(), lits.c_ptr(), coeffs.c_ptr(), res);
TRACE("farkas_learner", tout << "Add: " << mk_pp(res, m) << "\n";);
lemmas.push_back(res);
INSERT(res);
b_closed.mark(p, true);
}
}
@ -717,9 +723,10 @@ namespace pdr {
}
std::for_each(hyprefs.begin(), hyprefs.end(), delete_proc<expr_set>());
simplify_lemmas(lemmas);
}
void farkas_learner::get_asserted(proof* p, expr_set const& bs, ast_mark& b_closed, expr_ref_vector& lemmas) {
void farkas_learner::get_asserted(proof* p, expr_set const& bs, ast_mark& b_closed, obj_hashtable<expr>& lemma_set, expr_ref_vector& lemmas) {
ast_manager& m = lemmas.get_manager();
ast_mark visited;
proof* p0 = p;
@ -740,10 +747,11 @@ namespace pdr {
}
if (p->get_decl_kind() == PR_ASSERTED &&
bs.contains(m.get_fact(p))) {
expr* fact = m.get_fact(p);
TRACE("farkas_learner",
tout << mk_ll_pp(p0,m) << "\n";
tout << "Add: " << mk_pp(p,m) << "\n";);
lemmas.push_back(m.get_fact(p));
INSERT(fact);
b_closed.mark(p, true);
}
}

3
lib/pdr_farkas_learner.h
View file

@ -43,7 +43,6 @@ class farkas_learner {
front_end_params m_proof_params;
ast_manager m_pr;
scoped_ptr<smt::solver> m_ctx;
scoped_ptr<tactic> m_simplifier;
static front_end_params get_proof_params(front_end_params& orig_params);
@ -67,7 +66,7 @@ class farkas_learner {
bool is_farkas_lemma(ast_manager& m, expr* e);
void get_asserted(proof* p, expr_set const& bs, ast_mark& b_closed, expr_ref_vector& lemmas);
void get_asserted(proof* p, expr_set const& bs, ast_mark& b_closed, obj_hashtable<expr>& lemma_set, expr_ref_vector& lemmas);
bool is_pure_expr(func_decl_set const& symbs, expr* e) const;

6
lib/pdr_generalizers.cpp
View file

@ -100,7 +100,7 @@ namespace pdr {
ast_manager& m = core.get_manager();
TRACE("pdr", for (unsigned i = 0; i < core.size(); ++i) { tout << mk_pp(core[i].get(), m) << "\n"; } "\n";);
unsigned num_failures = 0, i = 0, num_changes = 0;
while (i < core.size() && (!m_failure_limit || num_failures <= m_failure_limit)) {
while (i < core.size() && 1 < core.size() && (!m_failure_limit || num_failures <= m_failure_limit)) {
expr_ref lit(m), state(m);
lit = core[i].get();
core[i] = m.mk_true();
@ -111,16 +111,18 @@ namespace pdr {
core[i] = core.back();
core.pop_back();
TRACE("pdr", tout << "Remove: " << mk_pp(lit, m) << "\n";);
IF_VERBOSE(3, verbose_stream() << "remove: " << mk_pp(lit, m) << "\n";);
++num_changes;
uses_level = uses_level_tmp;
}
else {
IF_VERBOSE(3, verbose_stream() << "keep: " << mk_pp(lit, m) << "\n";);
core[i] = lit;
++num_failures;
++i;
}
}
IF_VERBOSE(1, verbose_stream() << "changes: " << num_changes << " size: " << core.size() << "\n";);
IF_VERBOSE(2, verbose_stream() << "changes: " << num_changes << " size: " << core.size() << "\n";);
TRACE("pdr", tout << "changes: " << num_changes << " index: " << i << " size: " << core.size() << "\n";);
}