z3-z3-4.13.0.src.tactic.arith.purify_arith_tactic.cpp Maven / Gradle / Ivy
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/*++
Copyright (c) 2011 Microsoft Corporation
Module Name:
purify_arith_tactic.h
Abstract:
Tactic for eliminating arithmetic operators: DIV, IDIV, MOD,
TO_INT, and optionally (OP_IRRATIONAL_ALGEBRAIC_NUM).
This tactic uses the simplifier for also eliminating:
OP_SUB, OP_UMINUS, OP_POWER (optionally), OP_REM, OP_IS_INT.
Author:
Leonardo de Moura (leonardo) 2011-12-30.
Revision History:
--*/
#include "tactic/tactical.h"
#include "ast/rewriter/rewriter_def.h"
#include "ast/arith_decl_plugin.h"
#include "math/polynomial/algebraic_numbers.h"
#include "tactic/core/nnf_tactic.h"
#include "tactic/core/simplify_tactic.h"
#include "ast/rewriter/th_rewriter.h"
#include "ast/converters/generic_model_converter.h"
#include "ast/ast_smt2_pp.h"
#include "ast/ast_pp.h"
#include "ast/rewriter/expr_replacer.h"
/*
----
Some of the rules needed in the conversion are implemented in
arith_rewriter.cpp. Here is a summary of these rules:
(^ t (/ p q)) --> (^ (^ t (/ 1 q)) p)
(^ t n) --> t*...*t
when integer power expansion is requested
(is-int t) --> t = (to-real (to-int t))
(rem t1 t2) --> ite(t2 >= 0, (mod t1 t2), -(mod t1 t2))
----
The tactic implements a set of transformation rules. These rules
create fresh constants or (existential) variables, and add new
constraints to the context.
The context is the set of asserted formulas or a quantifier.
A rule is represented as:
From --> To | C
It means, any expression that matches From is replaced by To,
and the constraints C are added to the context.
For clarity reasons, I write the constraints using ad-hoc notation.
Rules
(^ t 0) --> k | t != 0 implies k = 1, t = 0 implies k = 0^0
where k is fresh
0^0 is a constant used to capture the meaning of (^ 0 0).
(^ t (/ 1 n)) --> k | t = k^n
when n is odd
where k is fresh
(^ t (/ 1 n)) --> k | t >= 0 implies t = k^n, t < 0 implies t = neg-root(t, n)
when n is even
where k is fresh
neg-root is a function symbol used to capture the meaning of a negative root
(root-obj p(x) i) --> k | p(k) = 0, l < k < u
when root object elimination is requested
where k is fresh
(l, u) is an isolating interval for the i-th root of p.
(to-int t) --> k | 0 <= to-real(k) - t < 1
where k is a fresh integer constant/variable
(/ t1 t2) --> k | t2 != 0 implies k*t2 = t1, t2 = 0 implies k = div-0(t1)
where k is fresh
div-0 is a function symbol used to capture the meaning of division by 0.
Remark: If it can be shown that t2 != 0, then the div-0(t1) function application
vanishes from the formula.
(div t1 t2) --> k1 | t2 = 0 \/ t1 = k1 * t2 + k2,
t2 = 0 \/ 0 <= k2,
t2 = 0 \/ k2 < |t2|,
t2 != 0 \/ k1 = idiv-0(t1),
t2 != 0 \/ k2 = mod-0(t1)
k1 is a fresh name for (div t1 t2)
k2 is a fresh name for (mod t1 t2)
(mod t1 t2) --> k2 | same constraints as above
*/
struct purify_arith_proc {
arith_util & m_util;
goal & m_goal;
bool m_produce_proofs;
bool m_elim_root_objs;
bool m_elim_inverses;
bool m_complete;
ast_mark m_unsafe_exprs;
bool m_unsafe_found;
obj_map > m_sin_cos;
expr_ref_vector m_pinned;
purify_arith_proc(goal & g, arith_util & u, bool produce_proofs, bool elim_root_objs, bool elim_inverses, bool complete):
m_util(u),
m_goal(g),
m_produce_proofs(produce_proofs),
m_elim_root_objs(elim_root_objs),
m_elim_inverses(elim_inverses),
m_complete(complete),
m_unsafe_found(false),
m_pinned(m()) {
}
arith_util & u() {
return m_util;
}
ast_manager & m() {
return u().get_manager();
}
struct find_unsafe_proc {
purify_arith_proc& m_owner;
find_unsafe_proc(purify_arith_proc& o) : m_owner(o) {}
void operator()(app* a) {
if (!m_owner.u().is_sin(a) &&
!m_owner.u().is_cos(a)) {
for (unsigned i = 0; i < a->get_num_args(); ++i) {
m_owner.m_unsafe_exprs.mark(a->get_arg(i), true);
}
}
}
void operator()(quantifier *q) {}
void operator()(var* v) {}
};
void find_unsafe() {
if (m_unsafe_found) return;
find_unsafe_proc proc(*this);
expr_fast_mark1 visited;
unsigned sz = m_goal.size();
for (unsigned i = 0; i < sz; i++) {
expr * curr = m_goal.form(i);
for_each_expr_core(proc, visited, curr);
}
m_unsafe_found = true;
}
bool convert_basis(expr* theta, expr*& x, expr*& y) {
if (!is_uninterp_const(theta)) {
return false;
}
find_unsafe();
if (m_unsafe_exprs.is_marked(theta)) {
return false;
}
std::pair pair;
if (!m_sin_cos.find(to_app(theta), pair)) {
pair.first = m().mk_fresh_const(nullptr, u().mk_real());
pair.second = m().mk_fresh_const(nullptr, u().mk_real());
m_sin_cos.insert(to_app(theta), pair);
m_pinned.push_back(pair.first);
m_pinned.push_back(pair.second);
m_pinned.push_back(theta);
// TBD for model conversion
}
x = pair.first;
y = pair.second;
return true;
}
struct bin_def {
expr* x, *y, *d;
bin_def(expr* x, expr* y, expr* d): x(x), y(y), d(d) {}
};
struct rw_cfg : public default_rewriter_cfg {
purify_arith_proc & m_owner;
obj_hashtable m_cannot_purify;
obj_map m_app2fresh;
obj_map m_app2pr;
expr_ref_vector m_pinned;
expr_ref_vector m_new_cnstrs;
proof_ref_vector m_new_cnstr_prs;
svector m_divs, m_idivs, m_mods;
expr_ref m_ipower0, m_rpower0;
expr_ref m_subst;
proof_ref m_subst_pr;
expr_ref_vector m_new_vars;
rw_cfg(purify_arith_proc & o):
m_owner(o),
m_pinned(o.m()),
m_new_cnstrs(o.m()),
m_new_cnstr_prs(o.m()),
m_ipower0(o.m()),
m_rpower0(o.m()),
m_subst(o.m()),
m_subst_pr(o.m()),
m_new_vars(o.m()) {
init_cannot_purify();
}
ast_manager & m() { return m_owner.m(); }
arith_util & u() { return m_owner.u(); }
bool produce_proofs() const { return m_owner.m_produce_proofs; }
bool complete() const { return m_owner.m_complete; }
bool elim_root_objs() const { return m_owner.m_elim_root_objs; }
bool elim_inverses() const { return m_owner.m_elim_inverses; }
void init_cannot_purify() {
struct proc {
rw_cfg& o;
proc(rw_cfg& o):o(o) {}
void operator()(app* a) {
for (expr* arg : *a) {
if (!is_ground(arg)) {
auto* f = a->get_decl();
o.m_cannot_purify.insert(f);
break;
}
}
}
void operator()(expr* ) {}
};
expr_fast_mark1 visited;
proc p(*this);
unsigned sz = m_owner.m_goal.size();
for (unsigned i = 0; i < sz; i++) {
expr* f = m_owner.m_goal.form(i);
for_each_expr_core(p, visited, f);
}
}
expr * mk_fresh_var(bool is_int) {
expr * r = m().mk_fresh_const(nullptr, is_int ? u().mk_int() : u().mk_real());
m_new_vars.push_back(r);
return r;
}
expr * mk_fresh_real_var() { return mk_fresh_var(false); }
expr * mk_fresh_int_var() { return mk_fresh_var(true); }
expr * mk_int_zero() { return u().mk_numeral(rational(0), true); }
expr * mk_real_zero() { return u().mk_numeral(rational(0), false); }
expr * mk_real_one() { return u().mk_numeral(rational(1), false); }
bool already_processed(app * t, expr_ref & result, proof_ref & result_pr) {
expr * r;
if (m_app2fresh.find(t, r)) {
result = r;
if (produce_proofs())
result_pr = m_app2pr.find(t);
return true;
}
return false;
}
void mk_def_proof(expr * k, expr * def, proof_ref & result_pr) {
result_pr = nullptr;
if (produce_proofs()) {
expr * eq = m().mk_eq(def, k);
proof * pr1 = m().mk_def_intro(eq);
result_pr = m().mk_apply_def(def, k, pr1);
}
}
void push_cnstr_pr(proof * def_pr) {
if (produce_proofs())
m_new_cnstr_prs.push_back(m().mk_th_lemma(u().get_family_id(), m_new_cnstrs.back(), 1, &def_pr));
}
void push_cnstr_pr(proof * def_pr1, proof * def_pr2) {
if (produce_proofs()) {
proof * prs[2] = { def_pr1, def_pr2 };
m_new_cnstr_prs.push_back(m().mk_th_lemma(u().get_family_id(), m_new_cnstrs.back(), 2, prs));
}
}
void push_cnstr(expr * cnstr) {
m_new_cnstrs.push_back(cnstr);
TRACE("purify_arith", tout << mk_pp(cnstr, m()) << "\n";);
}
void cache_result(app * t, expr * r, proof * pr) {
m_app2fresh.insert(t, r);
m_pinned.push_back(t);
m_pinned.push_back(r);
if (produce_proofs()) {
m_app2pr.insert(t, pr);
m_pinned.push_back(pr);
}
}
expr * OR(expr * arg1, expr * arg2) { return m().mk_or(arg1, arg2); }
expr * AND(expr * arg1, expr * arg2) { return m().mk_and(arg1, arg2); }
expr * EQ(expr * lhs, expr * rhs) { return m().mk_eq(lhs, rhs); }
expr * NOT(expr * arg) { return m().mk_not(arg); }
void process_div(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
app_ref t(m());
t = m().mk_app(f, num, args);
if (already_processed(t, result, result_pr))
return;
expr * k = mk_fresh_real_var();
result = k;
mk_def_proof(k, t, result_pr);
cache_result(t, result, result_pr);
expr * x = args[0];
expr * y = args[1];
// y = 0 \/ y*k = x
push_cnstr(OR(EQ(y, mk_real_zero()),
EQ(u().mk_mul(y, k), x)));
push_cnstr_pr(result_pr);
rational r;
if (complete()) {
// y != 0 \/ k = div-0(x)
push_cnstr(OR(NOT(EQ(y, mk_real_zero())),
EQ(k, u().mk_div(x, mk_real_zero()))));
push_cnstr_pr(result_pr);
}
m_divs.push_back(bin_def(x, y, k));
}
void process_idiv(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
app_ref div_app(m());
div_app = m().mk_app(f, num, args);
if (already_processed(div_app, result, result_pr))
return;
expr * k1 = mk_fresh_int_var();
result = k1;
mk_def_proof(k1, div_app, result_pr);
cache_result(div_app, result, result_pr);
expr * k2 = mk_fresh_int_var();
app_ref mod_app(m());
proof_ref mod_pr(m());
expr * x = args[0];
expr * y = args[1];
mod_app = u().mk_mod(x, y);
mk_def_proof(k2, mod_app, mod_pr);
cache_result(mod_app, k2, mod_pr);
m_mods.push_back(bin_def(x, y, k2));
// (div x y) --> k1 | y = 0 \/ x = k1 * y + k2,
// y = 0 \/ 0 <= k2,
// y = 0 \/ k2 < |y|,
// y != 0 \/ k1 = idiv-0(x),
// y != 0 \/ k2 = mod-0(x)
// We can write y = 0 \/ k2 < |y| as:
// y > 0 implies k2 < y ---> y <= 0 \/ k2 < y
// y < 0 implies k2 < -y ---> y >= 0 \/ k2 < -y
//
expr * zero = mk_int_zero();
push_cnstr(OR(EQ(y, zero), EQ(x, u().mk_add(u().mk_mul(k1, y), k2))));
push_cnstr_pr(result_pr, mod_pr);
push_cnstr(OR(EQ(y, zero), u().mk_le(zero, k2)));
push_cnstr_pr(mod_pr);
push_cnstr(OR(u().mk_le(y, zero), u().mk_lt(k2, y)));
push_cnstr_pr(mod_pr);
push_cnstr(OR(u().mk_ge(y, zero), u().mk_lt(k2, u().mk_mul(u().mk_numeral(rational(-1), true), y))));
push_cnstr_pr(mod_pr);
rational r;
if (complete() && (!u().is_numeral(y, r) || r.is_zero())) {
push_cnstr(OR(NOT(EQ(y, zero)), EQ(k1, u().mk_idiv(x, zero))));
push_cnstr_pr(result_pr);
push_cnstr(OR(NOT(EQ(y, zero)), EQ(k2, u().mk_mod(x, zero))));
push_cnstr_pr(mod_pr);
}
m_idivs.push_back(bin_def(x, y, k1));
}
void process_mod(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
app_ref t(m());
t = m().mk_app(f, num, args);
if (already_processed(t, result, result_pr))
return;
process_idiv(f, num, args, result, result_pr); // it will create mod
VERIFY(already_processed(t, result, result_pr));
}
void process_to_int(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
app_ref t(m());
t = m().mk_app(f, num, args);
if (already_processed(t, result, result_pr))
return;
expr * k = mk_fresh_int_var();
result = k;
mk_def_proof(k, t, result_pr);
cache_result(t, result, result_pr);
expr * x = args[0];
// 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(x - to-real(k) >= 1)
push_cnstr(NOT(u().mk_ge(diff, u().mk_numeral(rational(1), false))));
push_cnstr_pr(result_pr);
}
br_status process_power(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
rational y;
if (!u().is_numeral(args[1], y))
return BR_FAILED;
if (y.is_int() && !y.is_zero())
return BR_FAILED;
app_ref t(m());
t = m().mk_app(f, num, args);
if (already_processed(t, result, result_pr))
return BR_DONE;
expr * x = args[0];
bool is_int = u().is_int(x);
expr * k = mk_fresh_var(false);
result = k;
mk_def_proof(k, t, result_pr);
cache_result(t, result, result_pr);
expr_ref zero(u().mk_numeral(rational(0), is_int), m());
expr_ref one(u().mk_numeral(rational(1), is_int), m());
if (y.is_zero()) {
expr* p0;
if (is_int) {
if (!m_ipower0) m_ipower0 = mk_fresh_var(false);
p0 = m_ipower0;
}
else {
if (!m_rpower0) m_rpower0 = mk_fresh_var(false);
p0 = m_rpower0;
}
// (^ x 0) --> k | x != 0 implies k = 1, x = 0 implies k = 0^0
push_cnstr(OR(EQ(x, zero), EQ(k, one)));
push_cnstr_pr(result_pr);
push_cnstr(OR(NOT(EQ(x, zero)), EQ(k, p0)));
push_cnstr_pr(result_pr);
}
else if (!is_int) {
SASSERT(!y.is_int());
SASSERT(numerator(y).is_one());
rational n = denominator(y);
if (!n.is_even()) {
// (^ x (/ 1 n)) --> k | x = k^n
// when n is odd
push_cnstr(EQ(x, u().mk_power(k, u().mk_numeral(n, false))));
push_cnstr_pr(result_pr);
}
else {
SASSERT(n.is_even());
// (^ x (/ 1 n)) --> k | x >= 0 implies (x = k^n and k >= 0), x < 0 implies k = neg-root(x, n)
// when n is even
push_cnstr(OR(NOT(u().mk_ge(x, zero)),
AND(EQ(x, u().mk_power(k, u().mk_numeral(n, false))),
u().mk_ge(k, zero))));
push_cnstr_pr(result_pr);
push_cnstr(OR(u().mk_ge(x, zero),
EQ(k, u().mk_neg_root(x, u().mk_numeral(n, false)))));
push_cnstr_pr(result_pr);
}
// else {
// return BR_FAILED;
// }
}
else {
// root not supported for integers.
SASSERT(is_int);
SASSERT(!y.is_int());
return BR_FAILED;
}
return BR_DONE;
}
void process_irrat(app * s, expr_ref & result, proof_ref & result_pr) {
if (already_processed(s, result, result_pr))
return;
expr * k = mk_fresh_real_var();
result = k;
mk_def_proof(k, s, result_pr);
cache_result(s, result, result_pr);
anum_manager & am = u().am();
anum const & a = u().to_irrational_algebraic_numeral(s);
scoped_mpz_vector p(am.qm());
am.get_polynomial(a, p);
rational lower, upper;
am.get_lower(a, lower);
am.get_upper(a, upper);
unsigned sz = p.size();
SASSERT(sz > 2);
ptr_buffer args;
for (unsigned i = 0; i < sz; i++) {
if (am.qm().is_zero(p[i]))
continue;
rational coeff = rational(p[i]);
if (i == 0) {
args.push_back(u().mk_numeral(coeff, false));
}
else {
expr * m;
if (i == 1)
m = k;
else
m = u().mk_power(k, u().mk_numeral(rational(i), false));
args.push_back(u().mk_mul(u().mk_numeral(coeff, false), m));
}
}
SASSERT(args.size() >= 2);
push_cnstr(EQ(u().mk_add(args.size(), args.data()), mk_real_zero()));
push_cnstr_pr(result_pr);
push_cnstr(u().mk_lt(u().mk_numeral(lower, false), k));
push_cnstr_pr(result_pr);
push_cnstr(u().mk_lt(k, u().mk_numeral(upper, false)));
push_cnstr_pr(result_pr);
}
br_status process_sin_cos(bool first, func_decl *f, expr * theta, expr_ref & result, proof_ref & result_pr) {
expr* x, *y;
if (m_owner.convert_basis(theta, x, y)) {
result = first ? x : y;
app_ref t(m().mk_app(f, theta), m());
mk_def_proof(result, t, result_pr);
cache_result(t, result, result_pr);
push_cnstr(EQ(mk_real_one(), u().mk_add(u().mk_mul(x, x), u().mk_mul(y, y))));
push_cnstr_pr(result_pr);
return BR_DONE;
}
else {
expr_ref s(u().mk_sin(theta), m());
expr_ref c(u().mk_cos(theta), m());
expr_ref axm(EQ(mk_real_one(), u().mk_add(u().mk_mul(s, s), u().mk_mul(c, c))), m());
push_cnstr(axm);
push_cnstr_pr(m().mk_asserted(axm));
return BR_FAILED;
}
}
br_status process_sin(func_decl *f, expr * theta, expr_ref & result, proof_ref & result_pr) {
return process_sin_cos(true, f, theta, result, result_pr);
}
br_status process_cos(func_decl *f, expr * theta, expr_ref & result, proof_ref & result_pr) {
return process_sin_cos(false, f, theta, result, result_pr);
}
br_status process_asin(func_decl * f, expr * x, expr_ref & result, proof_ref & result_pr) {
if (!elim_inverses())
return BR_FAILED;
app_ref t(m());
t = m().mk_app(f, x);
if (already_processed(t, result, result_pr))
return BR_DONE;
expr * k = mk_fresh_var(false);
result = k;
mk_def_proof(k, t, result_pr);
cache_result(t, result, result_pr);
// Constraints:
// -1 <= x <= 1 implies sin(k) = x, -pi/2 <= k <= pi/2
// If complete()
// x < -1 implies k = asin_u(x)
// x > 1 implies k = asin_u(x)
expr * one = u().mk_numeral(rational(1), false);
expr * mone = u().mk_numeral(rational(-1), false);
expr * pi2 = u().mk_mul(u().mk_numeral(rational(1,2), false), u().mk_pi());
expr * mpi2 = u().mk_mul(u().mk_numeral(rational(-1,2), false), u().mk_pi());
// -1 <= x <= 1 implies sin(k) = x, -pi/2 <= k <= pi/2
push_cnstr(OR(OR(NOT(u().mk_ge(x, mone)),
NOT(u().mk_le(x, one))),
AND(EQ(x, u().mk_sin(k)),
AND(u().mk_ge(k, mpi2),
u().mk_le(k, pi2)))));
push_cnstr_pr(result_pr);
if (complete()) {
// x < -1 implies k = asin_u(x)
// x > 1 implies k = asin_u(x)
push_cnstr(OR(u().mk_ge(x, mone),
EQ(k, u().mk_u_asin(x))));
push_cnstr_pr(result_pr);
push_cnstr(OR(u().mk_le(x, one),
EQ(k, u().mk_u_asin(x))));
push_cnstr_pr(result_pr);
}
return BR_DONE;
}
br_status process_acos(func_decl * f, expr * x, expr_ref & result, proof_ref & result_pr) {
if (!elim_inverses())
return BR_FAILED;
app_ref t(m());
t = m().mk_app(f, x);
if (already_processed(t, result, result_pr))
return BR_DONE;
expr * k = mk_fresh_var(false);
result = k;
mk_def_proof(k, t, result_pr);
cache_result(t, result, result_pr);
// Constraints:
// -1 <= x <= 1 implies cos(k) = x, 0 <= k <= pi
// If complete()
// x < -1 implies k = acos_u(x)
// x > 1 implies k = acos_u(x)
expr * one = u().mk_numeral(rational(1), false);
expr * mone = u().mk_numeral(rational(-1), false);
expr * pi = u().mk_pi();
expr * zero = u().mk_numeral(rational(0), false);
// -1 <= x <= 1 implies cos(k) = x, 0 <= k <= pi
push_cnstr(OR(OR(NOT(u().mk_ge(x, mone)),
NOT(u().mk_le(x, one))),
AND(EQ(x, u().mk_cos(k)),
AND(u().mk_ge(k, zero),
u().mk_le(k, pi)))));
push_cnstr_pr(result_pr);
if (complete()) {
// x < -1 implies k = acos_u(x)
// x > 1 implies k = acos_u(x)
push_cnstr(OR(u().mk_ge(x, mone),
EQ(k, u().mk_u_acos(x))));
push_cnstr_pr(result_pr);
push_cnstr(OR(u().mk_le(x, one),
EQ(k, u().mk_u_acos(x))));
push_cnstr_pr(result_pr);
}
return BR_DONE;
}
br_status process_atan(func_decl * f, expr * x, expr_ref & result, proof_ref & result_pr) {
if (!elim_inverses())
return BR_FAILED;
app_ref t(m());
t = m().mk_app(f, x);
if (already_processed(t, result, result_pr))
return BR_DONE;
expr * k = mk_fresh_var(false);
result = k;
mk_def_proof(k, t, result_pr);
cache_result(t, result, result_pr);
// Constraints:
// tan(k) = x, -pi/2 < k < pi/2
expr * pi2 = u().mk_mul(u().mk_numeral(rational(1,2), false), u().mk_pi());
expr * mpi2 = u().mk_mul(u().mk_numeral(rational(-1,2), false), u().mk_pi());
push_cnstr(AND(EQ(x, u().mk_tan(k)),
AND(u().mk_gt(k, mpi2),
u().mk_lt(k, pi2))));
push_cnstr_pr(result_pr);
return BR_DONE;
}
br_status reduce_app(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
if (f->get_family_id() != u().get_family_id())
return BR_FAILED;
if (m_cannot_purify.contains(f))
return BR_FAILED;
switch (f->get_decl_kind()) {
case OP_DIV:
process_div(f, num, args, result, result_pr);
return BR_DONE;
case OP_IDIV:
if (!m_cannot_purify.empty())
return BR_FAILED;
process_idiv(f, num, args, result, result_pr);
return BR_DONE;
case OP_MOD:
if (!m_cannot_purify.empty())
return BR_FAILED;
process_mod(f, num, args, result, result_pr);
return BR_DONE;
case OP_TO_INT:
process_to_int(f, num, args, result, result_pr);
return BR_DONE;
case OP_POWER:
return process_power(f, num, args, result, result_pr);
case OP_ASIN:
return process_asin(f, args[0], result, result_pr);
case OP_ACOS:
return process_acos(f, args[0], result, result_pr);
case OP_SIN:
return process_sin(f, args[0], result, result_pr);
case OP_COS:
return process_cos(f, args[0], result, result_pr);
case OP_ATAN:
return process_atan(f, args[0], result, result_pr);
default:
return BR_FAILED;
}
}
bool get_subst(expr * s, expr * & t, proof * & t_pr) {
if (is_quantifier(s)) {
m_owner.process_quantifier(*this, to_quantifier(s), m_subst, m_subst_pr);
t = m_subst.get();
t_pr = m_subst_pr.get();
return true;
}
else if (u().is_irrational_algebraic_numeral(s) && elim_root_objs()) {
process_irrat(to_app(s), m_subst, m_subst_pr);
t = m_subst.get();
t_pr = m_subst_pr.get();
return true;
}
return false;
}
};
expr * mk_real_zero() { return u().mk_numeral(rational(0), false); }
struct rw : public rewriter_tpl {
rw_cfg m_cfg;
rw(purify_arith_proc & o):
rewriter_tpl(o.m(), o.m_produce_proofs, m_cfg),
m_cfg(o) {
}
};
struct rw_rec : public rewriter_tpl {
rw_cfg& m_cfg;
rw_rec(rw_cfg& cfg):
rewriter_tpl(cfg.m(), cfg.produce_proofs(), cfg),
m_cfg(cfg) {
}
};
void process_quantifier(rw_cfg& cfg, quantifier * q, expr_ref & result, proof_ref & result_pr) {
result_pr = nullptr;
rw_rec r(cfg);
expr_ref new_body(m());
proof_ref new_body_pr(m());
r(q->get_expr(), new_body, new_body_pr);
TRACE("purify_arith",
tout << "body: " << mk_ismt2_pp(q->get_expr(), m()) << "\nnew_body: " << new_body << "\n";);
result = m().update_quantifier(q, new_body);
if (m_produce_proofs) {
result_pr = m().mk_rewrite(q->get_expr(), new_body);
result_pr = m().mk_quant_intro(q, to_quantifier(result.get()), result_pr);
}
}
void operator()(model_converter_ref & mc, bool produce_models) {
rw r(*this);
// purify
expr_ref new_curr(m());
proof_ref new_pr(m());
unsigned sz = m_goal.size();
for (unsigned i = 0; !m_goal.inconsistent() && i < sz; i++) {
expr * curr = m_goal.form(i);
r(curr, new_curr, new_pr);
if (m_produce_proofs) {
proof * pr = m_goal.pr(i);
new_pr = m().mk_modus_ponens(pr, new_pr);
}
m_goal.update(i, new_curr, new_pr, m_goal.dep(i));
}
// add constraints
sz = r.cfg().m_new_cnstrs.size();
TRACE("purify_arith", tout << r.cfg().m_new_cnstrs << "\n";);
TRACE("purify_arith", tout << r.cfg().m_new_cnstr_prs << "\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) : nullptr, nullptr);
}
auto const& divs = r.cfg().m_divs;
auto const& idivs = r.cfg().m_idivs;
auto const& mods = r.cfg().m_mods;
for (unsigned i = 0; i < divs.size(); ++i) {
auto const& p1 = divs[i];
for (unsigned j = i + 1; j < divs.size(); ++j) {
auto const& p2 = divs[j];
m_goal.assert_expr(m().mk_implies(
m().mk_and(m().mk_eq(p1.x, p2.x), m().mk_eq(p1.y, p2.y)),
m().mk_eq(p1.d, p2.d)));
}
}
for (unsigned i = 0; i < mods.size(); ++i) {
auto const& p1 = mods[i];
for (unsigned j = i + 1; j < mods.size(); ++j) {
auto const& p2 = mods[j];
m_goal.assert_expr(m().mk_implies(
m().mk_and(m().mk_eq(p1.x, p2.x), m().mk_eq(p1.y, p2.y)),
m().mk_eq(p1.d, p2.d)));
}
}
for (unsigned i = 0; i < idivs.size(); ++i) {
auto const& p1 = idivs[i];
for (unsigned j = i + 1; j < idivs.size(); ++j) {
auto const& p2 = idivs[j];
m_goal.assert_expr(m().mk_implies(
m().mk_and(m().mk_eq(p1.x, p2.x), m().mk_eq(p1.y, p2.y)),
m().mk_eq(p1.d, p2.d)));
}
}
// add generic_model_converter to eliminate auxiliary variables from model
if (produce_models) {
generic_model_converter * fmc = alloc(generic_model_converter, m(), "purify");
mc = fmc;
obj_map & f2v = r.cfg().m_app2fresh;
for (auto const& kv : f2v) {
app * v = to_app(kv.m_value);
SASSERT(is_uninterp_const(v));
fmc->hide(v->get_decl());
}
if (!divs.empty()) {
expr_ref body(u().mk_real(0), m());
expr_ref v0(m().mk_var(0, u().mk_real()), m());
expr_ref v1(m().mk_var(1, u().mk_real()), m());
for (auto const& p : divs) {
body = m().mk_ite(m().mk_and(m().mk_eq(v0, p.x), m().mk_eq(v1, p.y)), p.d, body);
}
fmc->add(u().mk_div0(), body);
}
if (!mods.empty()) {
expr_ref body(u().mk_int(0), m());
expr_ref v0(m().mk_var(0, u().mk_int()), m());
expr_ref v1(m().mk_var(1, u().mk_int()), m());
for (auto const& p : mods) {
body = m().mk_ite(m().mk_and(m().mk_eq(v0, p.x), m().mk_eq(v1, p.y)), p.d, body);
}
fmc->add(u().mk_mod0(), body);
body = m().mk_ite(u().mk_ge(v1, u().mk_int(0)), body, u().mk_uminus(body));
fmc->add(u().mk_rem0(), body);
}
if (!idivs.empty()) {
expr_ref body(u().mk_int(0), m());
expr_ref v0(m().mk_var(0, u().mk_int()), m());
expr_ref v1(m().mk_var(1, u().mk_int()), m());
for (auto const& p : idivs) {
body = m().mk_ite(m().mk_and(m().mk_eq(v0, p.x), m().mk_eq(v1, p.y)), p.d, body);
}
fmc->add(u().mk_idiv0(), body);
}
if (r.cfg().m_ipower0) {
fmc->add(u().mk_ipower0(), r.cfg().m_ipower0);
}
if (r.cfg().m_rpower0) {
fmc->add(u().mk_rpower0(), r.cfg().m_rpower0);
}
}
if (produce_models && !m_sin_cos.empty()) {
generic_model_converter* emc = alloc(generic_model_converter, m(), "purify_sin_cos");
mc = concat(mc.get(), emc);
for (auto const& kv : m_sin_cos) {
emc->add(kv.m_key->get_decl(),
m().mk_ite(u().mk_ge(kv.m_value.first, mk_real_zero()), u().mk_acos(kv.m_value.second),
u().mk_add(u().mk_acos(u().mk_uminus(kv.m_value.second)), u().mk_pi())));
}
}
}
};
class purify_arith_tactic : public tactic {
arith_util m_util;
params_ref m_params;
public:
purify_arith_tactic(ast_manager & m, params_ref const & p):
m_util(m),
m_params(p) {
}
tactic * translate(ast_manager & m) override {
return alloc(purify_arith_tactic, m, m_params);
}
char const* name() const override { return "purify_arith"; }
void updt_params(params_ref const & p) override {
m_params.append(p);
}
void collect_param_descrs(param_descrs & r) override {
r.insert("complete", CPK_BOOL,
"add constraints to make sure that any interpretation of a underspecified arithmetic operators is a function. The result will include additional uninterpreted functions/constants: /0, div0, mod0, 0^0, neg-root", "true");
r.insert("elim_root_objects", CPK_BOOL,
"eliminate root objects.", "true");
r.insert("elim_inverses", CPK_BOOL,
"eliminate inverse trigonometric functions (asin, acos, atan).", "true");
th_rewriter::get_param_descrs(r);
}
void operator()(goal_ref const & g,
goal_ref_buffer & result) override {
try {
tactic_report report("purify-arith", *g);
TRACE("goal", 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);
bool elim_inverses = m_params.get_bool("elim_inverses", true);
bool complete = m_params.get_bool("complete", true);
purify_arith_proc proc(*(g.get()), m_util, produce_proofs, elim_root_objs, elim_inverses, complete);
model_converter_ref mc;
proc(mc, produce_models);
g->add(mc.get());
g->inc_depth();
result.push_back(g.get());
}
catch (rewriter_exception & ex) {
throw tactic_exception(ex.msg());
}
}
void cleanup() override {
}
};
tactic * mk_purify_arith_tactic(ast_manager & m, params_ref const & p) {
params_ref elim_rem_p = p;
elim_rem_p.set_bool("elim_rem", true);
params_ref skolemize_p;
skolemize_p.set_bool("skolemize", false);
return and_then(using_params(mk_snf_tactic(m, skolemize_p), skolemize_p),
using_params(mk_simplify_tactic(m, elim_rem_p), elim_rem_p),
alloc(purify_arith_tactic, m, p),
mk_simplify_tactic(m, p));
}