diff --git a/src/api/api_solver.cpp b/src/api/api_solver.cpp
index 53ce36720..0c94c0b4e 100644
--- a/src/api/api_solver.cpp
+++ b/src/api/api_solver.cpp
@@ -529,9 +529,9 @@ extern "C" {
Z3_CATCH_RETURN(Z3_L_UNDEF);
}
- Z3_ast Z3_API Z3_solver_cube(Z3_context c, Z3_solver s) {
+ Z3_ast Z3_API Z3_solver_cube(Z3_context c, Z3_solver s, unsigned cutoff) {
Z3_TRY;
- LOG_Z3_solver_cube(c, s);
+ LOG_Z3_solver_cube(c, s, cutoff);
ast_manager& m = mk_c(c)->m();
expr_ref result(m);
unsigned timeout = to_solver(s)->m_params.get_uint("timeout", mk_c(c)->get_timeout());
@@ -544,7 +544,7 @@ extern "C" {
scoped_timer timer(timeout, &eh);
scoped_rlimit _rlimit(mk_c(c)->m().limit(), rlimit);
try {
- result = to_solver_ref(s)->cube();
+ result = to_solver_ref(s)->cube(cutoff);
}
catch (z3_exception & ex) {
mk_c(c)->handle_exception(ex);
diff --git a/src/api/dotnet/Solver.cs b/src/api/dotnet/Solver.cs
index 9154117ce..4a779e91b 100644
--- a/src/api/dotnet/Solver.cs
+++ b/src/api/dotnet/Solver.cs
@@ -353,6 +353,12 @@ namespace Microsoft.Z3
}
}
+ ///
+ /// Backtrack level that can be adjusted by conquer process
+ ///
+ public uint BacktrackLevel { get; set; }
+
+
///
/// Return a set of cubes.
///
@@ -360,10 +366,8 @@ namespace Microsoft.Z3
{
int rounds = 0;
while (true) {
- BoolExpr r = (BoolExpr)Expr.Create(Context, Native.Z3_solver_cube(Context.nCtx, NativeObject));
+ BoolExpr r = (BoolExpr)Expr.Create(Context, Native.Z3_solver_cube(Context.nCtx, NativeObject, BacktrackLevel));
if (r.IsFalse) {
- if (rounds == 0)
- yield return r;
break;
}
if (r.IsTrue) {
@@ -412,6 +416,7 @@ namespace Microsoft.Z3
: base(ctx, obj)
{
Contract.Requires(ctx != null);
+ this.BacktrackLevel = uint.MaxValue;
}
internal class DecRefQueue : IDecRefQueue
diff --git a/src/api/python/z3/z3.py b/src/api/python/z3/z3.py
index 6b6c90019..2ae7e6ced 100644
--- a/src/api/python/z3/z3.py
+++ b/src/api/python/z3/z3.py
@@ -5988,6 +5988,7 @@ class Solver(Z3PPObject):
def __init__(self, solver=None, ctx=None):
assert solver is None or ctx is not None
self.ctx = _get_ctx(ctx)
+ self.backtrack_level = 4000000000
self.solver = None
if solver is None:
self.solver = Z3_mk_solver(self.ctx.ref())
@@ -6285,17 +6286,13 @@ class Solver(Z3PPObject):
def cube(self):
"""Get set of cubes"""
- rounds = 0
while True:
- r = _to_expr_ref(Z3_solver_cube(self.ctx.ref(), self.solver), self.ctx)
+ r = _to_expr_ref(Z3_solver_cube(self.ctx.ref(), self.solver, self.backtrack_level), self.ctx)
if (is_false(r)):
- if (rounds == 0):
- yield r
return
if (is_true(r)):
yield r
return
- rounds += 1
yield r
def proof(self):
diff --git a/src/api/z3_api.h b/src/api/z3_api.h
index ffda1ecbd..b17e2a531 100644
--- a/src/api/z3_api.h
+++ b/src/api/z3_api.h
@@ -6232,10 +6232,13 @@ extern "C" {
The number of (non-constant) cubes is by default 1. For the sat solver cubing is controlled
using parameters sat.lookahead.cube.cutoff and sat.lookahead.cube.fraction.
- def_API('Z3_solver_cube', AST, (_in(CONTEXT), _in(SOLVER)))
+ The last argument is a backtracking level. It instructs the cube process to backtrack below
+ the indicated level for the next cube.
+
+ def_API('Z3_solver_cube', AST, (_in(CONTEXT), _in(SOLVER), _in(UINT)))
*/
- Z3_ast Z3_API Z3_solver_cube(Z3_context c, Z3_solver s);
+ Z3_ast Z3_API Z3_solver_cube(Z3_context c, Z3_solver s, unsigned backtrack_level);
/**
\brief Retrieve the model for the last #Z3_solver_check or #Z3_solver_check_assumptions
diff --git a/src/muz/spacer/spacer_itp_solver.h b/src/muz/spacer/spacer_itp_solver.h
index 6fc67a243..c61dba13c 100644
--- a/src/muz/spacer/spacer_itp_solver.h
+++ b/src/muz/spacer/spacer_itp_solver.h
@@ -119,7 +119,7 @@ public:
{NOT_IMPLEMENTED_YET();}
virtual void assert_lemma(expr* e) { NOT_IMPLEMENTED_YET(); }
virtual expr_ref lookahead(const expr_ref_vector &,const expr_ref_vector &) { return expr_ref(m.mk_true(), m); }
- virtual expr_ref cube() { return expr_ref(m.mk_true(), m); }
+ virtual expr_ref cube(unsigned) { return expr_ref(m.mk_true(), m); }
virtual void push();
diff --git a/src/muz/spacer/spacer_virtual_solver.h b/src/muz/spacer/spacer_virtual_solver.h
index 4e1f43bfc..4818600a9 100644
--- a/src/muz/spacer/spacer_virtual_solver.h
+++ b/src/muz/spacer/spacer_virtual_solver.h
@@ -94,7 +94,7 @@ public:
virtual void reset();
virtual void set_progress_callback(progress_callback *callback) {UNREACHABLE();}
- virtual expr_ref cube() { return expr_ref(m.mk_true(), m); }
+ virtual expr_ref cube(unsigned) { return expr_ref(m.mk_true(), m); }
virtual solver *translate(ast_manager &m, params_ref const &p);
diff --git a/src/opt/opt_solver.h b/src/opt/opt_solver.h
index 1f0a518b2..f695bae28 100644
--- a/src/opt/opt_solver.h
+++ b/src/opt/opt_solver.h
@@ -108,7 +108,7 @@ namespace opt {
virtual ast_manager& get_manager() const { return m; }
virtual lbool find_mutexes(expr_ref_vector const& vars, vector& mutexes);
virtual lbool preferred_sat(expr_ref_vector const& asms, vector& cores);
- virtual expr_ref cube() { return expr_ref(m.mk_true(), m); }
+ virtual expr_ref cube(unsigned) { return expr_ref(m.mk_true(), m); }
void set_logic(symbol const& logic);
smt::theory_var add_objective(app* term);
diff --git a/src/sat/sat_lookahead.cpp b/src/sat/sat_lookahead.cpp
index a41468936..27d174653 100644
--- a/src/sat/sat_lookahead.cpp
+++ b/src/sat/sat_lookahead.cpp
@@ -1964,7 +1964,7 @@ namespace sat {
bool_var_vector vars;
for (bool_var v : m_freevars) vars.push_back(v);
while (true) {
- lbool result = cube(vars, lits);
+ lbool result = cube(vars, lits, UINT_MAX);
if (lits.empty() || result != l_undef) {
return l_undef;
}
@@ -1973,7 +1973,7 @@ namespace sat {
return l_undef;
}
- lbool lookahead::cube(bool_var_vector const& vars, literal_vector& lits) {
+ lbool lookahead::cube(bool_var_vector const& vars, literal_vector& lits, unsigned backtrack_level) {
scoped_ext _scoped_ext(*this);
lits.reset();
m_select_lookahead_vars.reset();
@@ -2006,6 +2006,14 @@ namespace sat {
continue;
}
pick_up_work:
+ if (m_cube_state.m_cube.size() >= backtrack_level) {
+ IF_VERBOSE(10, verbose_stream() << "(sat-cube :cube: " << m_cube_state.m_cube.size() << " :backtrack_level " << backtrack_level << ")\n";);
+ while (m_cube_state.m_cube.size() >= backtrack_level) {
+ set_conflict();
+ backtrack(m_cube_state.m_cube, m_cube_state.m_is_decision);
+ }
+ }
+ backtrack_level = UINT_MAX;
depth = m_cube_state.m_cube.size();
if ((m_config.m_cube_cutoff != 0 && depth == m_config.m_cube_cutoff) ||
(m_config.m_cube_cutoff == 0 && m_freevars.size() < m_cube_state.m_freevars_threshold)) {
diff --git a/src/sat/sat_lookahead.h b/src/sat/sat_lookahead.h
index baf3ed660..6cf75937f 100644
--- a/src/sat/sat_lookahead.h
+++ b/src/sat/sat_lookahead.h
@@ -567,7 +567,7 @@ namespace sat {
lbool cube();
- lbool cube(bool_var_vector const& vars, literal_vector& lits);
+ lbool cube(bool_var_vector const& vars, literal_vector& lits, unsigned backtrack_level);
literal select_lookahead(literal_vector const& assumptions, bool_var_vector const& vars);
/**
diff --git a/src/sat/sat_solver.cpp b/src/sat/sat_solver.cpp
index ba6e63680..61dc1f6c2 100644
--- a/src/sat/sat_solver.cpp
+++ b/src/sat/sat_solver.cpp
@@ -837,11 +837,11 @@ namespace sat {
return lh.select_lookahead(assumptions, vars);
}
- lbool solver::cube(bool_var_vector const& vars, literal_vector& lits) {
+ lbool solver::cube(bool_var_vector const& vars, literal_vector& lits, unsigned backtrack_level) {
if (!m_cuber) {
m_cuber = alloc(lookahead, *this);
}
- lbool result = m_cuber->cube(vars, lits);
+ lbool result = m_cuber->cube(vars, lits, backtrack_level);
if (result == l_false) {
dealloc(m_cuber);
m_cuber = nullptr;
diff --git a/src/sat/sat_solver.h b/src/sat/sat_solver.h
index bf5f0975b..cb8c2b763 100644
--- a/src/sat/sat_solver.h
+++ b/src/sat/sat_solver.h
@@ -352,7 +352,7 @@ namespace sat {
bool check_clauses(model const& m) const;
literal select_lookahead(literal_vector const& assumptions, bool_var_vector const& vars);
- lbool cube(bool_var_vector const& vars, literal_vector& lits);
+ lbool cube(bool_var_vector const& vars, literal_vector& lits, unsigned backtrack_level);
protected:
unsigned m_conflicts_since_init;
diff --git a/src/sat/sat_solver/inc_sat_solver.cpp b/src/sat/sat_solver/inc_sat_solver.cpp
index b9bc81e3d..98c42ed19 100644
--- a/src/sat/sat_solver/inc_sat_solver.cpp
+++ b/src/sat/sat_solver/inc_sat_solver.cpp
@@ -301,7 +301,7 @@ public:
return 0;
}
- virtual expr_ref cube() {
+ virtual expr_ref cube(unsigned backtrack_level) {
if (!m_internalized) {
dep2asm_t dep2asm;
m_model = 0;
@@ -315,7 +315,7 @@ public:
vars.push_back(kv.m_value);
}
sat::literal_vector lits;
- lbool result = m_solver.cube(vars, lits);
+ lbool result = m_solver.cube(vars, lits, backtrack_level);
if (result == l_false || lits.empty()) {
return expr_ref(m.mk_false(), m);
}
diff --git a/src/smt/smt_solver.cpp b/src/smt/smt_solver.cpp
index b37d004f4..1a0e6facd 100644
--- a/src/smt/smt_solver.cpp
+++ b/src/smt/smt_solver.cpp
@@ -226,7 +226,7 @@ namespace smt {
return expr_ref(m.mk_true(), m);
}
- virtual expr_ref cube() {
+ virtual expr_ref cube(unsigned) {
ast_manager& m = get_manager();
return expr_ref(m.mk_true(), m);
}
diff --git a/src/solver/combined_solver.cpp b/src/solver/combined_solver.cpp
index 05e75a9a4..7d41a8685 100644
--- a/src/solver/combined_solver.cpp
+++ b/src/solver/combined_solver.cpp
@@ -281,8 +281,8 @@ public:
return m_solver1->get_num_assumptions() + m_solver2->get_num_assumptions();
}
- virtual expr_ref cube() {
- return m_solver1->cube();
+ virtual expr_ref cube(unsigned backtrack_level) {
+ return m_solver1->cube(backtrack_level);
}
virtual expr * get_assumption(unsigned idx) const {
diff --git a/src/solver/solver.h b/src/solver/solver.h
index d0e70546b..a3454a798 100644
--- a/src/solver/solver.h
+++ b/src/solver/solver.h
@@ -189,7 +189,7 @@ public:
\brief extract a lookahead candidates for branching.
*/
- virtual expr_ref cube() = 0;
+ virtual expr_ref cube(unsigned backtrack_level) = 0;
/**
\brief Display the content of this solver.
diff --git a/src/solver/solver_pool.cpp b/src/solver/solver_pool.cpp
index b2da00bfa..afefd8433 100644
--- a/src/solver/solver_pool.cpp
+++ b/src/solver/solver_pool.cpp
@@ -223,7 +223,7 @@ public:
virtual void get_labels(svector & r) { return m_base->get_labels(r); }
virtual void set_progress_callback(progress_callback * callback) { m_base->set_progress_callback(callback); }
- virtual expr_ref cube() { return expr_ref(m.mk_true(), m); }
+ virtual expr_ref cube(unsigned ) { return expr_ref(m.mk_true(), m); }
virtual ast_manager& get_manager() const { return m_base->get_manager(); }
diff --git a/src/solver/tactic2solver.cpp b/src/solver/tactic2solver.cpp
index dc9f1b25f..607f0994f 100644
--- a/src/solver/tactic2solver.cpp
+++ b/src/solver/tactic2solver.cpp
@@ -77,7 +77,7 @@ public:
virtual ast_manager& get_manager() const;
- virtual expr_ref cube() {
+ virtual expr_ref cube(unsigned ) {
ast_manager& m = get_manager();
return expr_ref(m.mk_true(), m);
}
diff --git a/src/tactic/portfolio/bounded_int2bv_solver.cpp b/src/tactic/portfolio/bounded_int2bv_solver.cpp
index 195a16fbf..da031171d 100644
--- a/src/tactic/portfolio/bounded_int2bv_solver.cpp
+++ b/src/tactic/portfolio/bounded_int2bv_solver.cpp
@@ -163,7 +163,7 @@ public:
virtual void set_reason_unknown(char const* msg) { m_solver->set_reason_unknown(msg); }
virtual void get_labels(svector & r) { m_solver->get_labels(r); }
virtual ast_manager& get_manager() const { return m; }
- virtual expr_ref cube() { flush_assertions(); return m_solver->cube(); }
+ virtual expr_ref cube(unsigned backtrack_level) { flush_assertions(); return m_solver->cube(backtrack_level); }
virtual lbool find_mutexes(expr_ref_vector const& vars, vector& mutexes) { return m_solver->find_mutexes(vars, mutexes); }
virtual lbool get_consequences_core(expr_ref_vector const& asms, expr_ref_vector const& vars, expr_ref_vector& consequences) {
flush_assertions();
diff --git a/src/tactic/portfolio/enum2bv_solver.cpp b/src/tactic/portfolio/enum2bv_solver.cpp
index b16ba2443..474084650 100644
--- a/src/tactic/portfolio/enum2bv_solver.cpp
+++ b/src/tactic/portfolio/enum2bv_solver.cpp
@@ -113,7 +113,7 @@ public:
virtual void get_labels(svector & r) { m_solver->get_labels(r); }
virtual ast_manager& get_manager() const { return m; }
virtual lbool find_mutexes(expr_ref_vector const& vars, vector& mutexes) { return m_solver->find_mutexes(vars, mutexes); }
- virtual expr_ref cube() { return m_solver->cube(); }
+ virtual expr_ref cube(unsigned backtrack_level) { return m_solver->cube(backtrack_level); }
virtual lbool get_consequences_core(expr_ref_vector const& asms, expr_ref_vector const& vars, expr_ref_vector& consequences) {
datatype_util dt(m);
diff --git a/src/tactic/portfolio/parallel_tactic.cpp b/src/tactic/portfolio/parallel_tactic.cpp
index 7651ace16..7d25f0f7e 100644
--- a/src/tactic/portfolio/parallel_tactic.cpp
+++ b/src/tactic/portfolio/parallel_tactic.cpp
@@ -414,7 +414,7 @@ private:
cubes.reset();
s.set_cube_params();
while (true) {
- expr_ref c = s.get_solver().cube();
+ expr_ref c = s.get_solver().cube(UINT_MAX); // TBD tune this
VERIFY(c);
if (m.is_false(c)) {
break;
diff --git a/src/tactic/portfolio/pb2bv_solver.cpp b/src/tactic/portfolio/pb2bv_solver.cpp
index 22303f62a..4f4c044b8 100644
--- a/src/tactic/portfolio/pb2bv_solver.cpp
+++ b/src/tactic/portfolio/pb2bv_solver.cpp
@@ -103,7 +103,7 @@ public:
virtual void set_reason_unknown(char const* msg) { m_solver->set_reason_unknown(msg); }
virtual void get_labels(svector & r) { m_solver->get_labels(r); }
virtual ast_manager& get_manager() const { return m; }
- virtual expr_ref cube() { flush_assertions(); return m_solver->cube(); }
+ virtual expr_ref cube(unsigned backtrack_level) { flush_assertions(); return m_solver->cube(backtrack_level); }
virtual lbool find_mutexes(expr_ref_vector const& vars, vector& mutexes) { return m_solver->find_mutexes(vars, mutexes); }
virtual lbool get_consequences_core(expr_ref_vector const& asms, expr_ref_vector const& vars, expr_ref_vector& consequences) {
flush_assertions();