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z3/src/ast/rewriter/arith_rewriter.cpp
Leonardo de Moura cf28cbab0a saved params work 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2012-11-29 17:19:12 -08:00

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/*++
Copyright (c) 2011 Microsoft Corporation
Module Name:
arith_rewriter.cpp
Abstract:
Basic rewriting rules for arithmetic
Author:
Leonardo (leonardo) 2011-04-10
Notes:
--*/
#include"arith_rewriter.h"
#include"poly_rewriter_def.h"
#include"algebraic_numbers.h"
#include"ast_pp.h"
void arith_rewriter::updt_local_params(params_ref const & p) {
m_arith_lhs = p.get_bool("arith_lhs", false);
m_gcd_rounding = p.get_bool("gcd_rounding", false);
m_eq2ineq = p.get_bool("eq2ineq", false);
m_elim_to_real = p.get_bool("elim_to_real", false);
m_push_to_real = p.get_bool("push_to_real", true);
m_anum_simp = p.get_bool("algebraic_number_evaluator", true);
m_max_degree = p.get_uint("max_degree", 64);
m_expand_power = p.get_bool("expand_power", false);
m_mul2power = p.get_bool("mul_to_power", false);
m_elim_rem = p.get_bool("elim_rem", false);
m_expand_tan = p.get_bool("expand_tan", false);
set_sort_sums(p.get_bool("sort_sums", false)); // set here to avoid collision with bvadd
}
void arith_rewriter::updt_params(params_ref const & p) {
poly_rewriter<arith_rewriter_core>::updt_params(p);
updt_local_params(p);
}
void arith_rewriter::get_param_descrs(param_descrs & r) {
poly_rewriter<arith_rewriter_core>::get_param_descrs(r);
r.insert("algebraic_number_evaluator", CPK_BOOL, "(default: true) simplify/evaluate expressions containing (algebraic) irrational numbers.");
r.insert("mul_to_power", CPK_BOOL, "(default: false) collpase (* t ... t) into (^ t k), it is ignored if expand_power is true.");
r.insert("expand_power", CPK_BOOL, "(default: false) expand (^ t k) into (* t ... t) if 1 < k <= max_degree.");
r.insert("expand_tan", CPK_BOOL, "(default: false) replace (tan x) with (/ (sin x) (cos x)).");
r.insert("max_degree", CPK_UINT, "(default: 64) max degree of algebraic numbers (and power operators) processed by simplifier.");
r.insert("eq2ineq", CPK_BOOL, "(default: false) split arithmetic equalities into two inequalities.");
r.insert("sort_sums", CPK_BOOL, "(default: false) sort the arguments of + application.");
r.insert("gcd_rounding", CPK_BOOL, "(default: false) use gcd rounding on integer arithmetic atoms.");
r.insert("arith_lhs", CPK_BOOL, "(default: false) all monomials are moved to the left-hand-side, and the right-hand-side is just a constant.");
r.insert("elim_to_real", CPK_BOOL, "(default: false) eliminate to_real from arithmetic predicates that contain only integers.");
r.insert("push_to_real", CPK_BOOL, "(default: true) distribute to_real over * and +.");
r.insert("elim_rem", CPK_BOOL, "(default: false) replace (rem x y) with (ite (>= y 0) (mod x y) (- (mod x y))).");
}
br_status arith_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * const * args, expr_ref & result) {
br_status st = BR_FAILED;
SASSERT(f->get_family_id() == get_fid());
switch (f->get_decl_kind()) {
case OP_NUM: st = BR_FAILED; break;
case OP_IRRATIONAL_ALGEBRAIC_NUM: st = BR_FAILED; break;
case OP_LE: SASSERT(num_args == 2); st = mk_le_core(args[0], args[1], result); break;
case OP_GE: SASSERT(num_args == 2); st = mk_ge_core(args[0], args[1], result); break;
case OP_LT: SASSERT(num_args == 2); st = mk_lt_core(args[0], args[1], result); break;
case OP_GT: SASSERT(num_args == 2); st = mk_gt_core(args[0], args[1], result); break;
case OP_ADD: st = mk_add_core(num_args, args, result); break;
case OP_MUL: st = mk_mul_core(num_args, args, result); break;
case OP_SUB: st = mk_sub(num_args, args, result); break;
case OP_DIV: SASSERT(num_args == 2); st = mk_div_core(args[0], args[1], result); break;
case OP_IDIV: SASSERT(num_args == 2); st = mk_idiv_core(args[0], args[1], result); break;
case OP_MOD: SASSERT(num_args == 2); st = mk_mod_core(args[0], args[1], result); break;
case OP_REM: SASSERT(num_args == 2); st = mk_rem_core(args[0], args[1], result); break;
case OP_UMINUS: SASSERT(num_args == 1); st = mk_uminus(args[0], result); break;
case OP_TO_REAL: SASSERT(num_args == 1); st = mk_to_real_core(args[0], result); break;
case OP_TO_INT: SASSERT(num_args == 1); st = mk_to_int_core(args[0], result); break;
case OP_IS_INT: SASSERT(num_args == 1); st = mk_is_int(args[0], result); break;
case OP_POWER: SASSERT(num_args == 2); st = mk_power_core(args[0], args[1], result); break;
case OP_SIN: SASSERT(num_args == 1); st = mk_sin_core(args[0], result); break;
case OP_COS: SASSERT(num_args == 1); st = mk_cos_core(args[0], result); break;
case OP_TAN: SASSERT(num_args == 1); st = mk_tan_core(args[0], result); break;
case OP_ASIN: SASSERT(num_args == 1); st = mk_asin_core(args[0], result); break;
case OP_ACOS: SASSERT(num_args == 1); st = mk_acos_core(args[0], result); break;
case OP_ATAN: SASSERT(num_args == 1); st = mk_atan_core(args[0], result); break;
case OP_SINH: SASSERT(num_args == 1); st = mk_sinh_core(args[0], result); break;
case OP_COSH: SASSERT(num_args == 1); st = mk_cosh_core(args[0], result); break;
case OP_TANH: SASSERT(num_args == 1); st = mk_tanh_core(args[0], result); break;
default: st = BR_FAILED; break;
}
CTRACE("arith_rewriter", st != BR_FAILED, tout << mk_pp(f, m());
for (unsigned i = 0; i < num_args; ++i) tout << mk_pp(args[i], m()) << " ";
tout << "\n==>\n" << mk_pp(result.get(), m()) << "\n";);
return st;
}
void arith_rewriter::get_coeffs_gcd(expr * t, numeral & g, bool & first, unsigned & num_consts) {
unsigned sz;
expr * const * ms = get_monomials(t, sz);
SASSERT(sz >= 1);
numeral a;
for (unsigned i = 0; i < sz; i++) {
expr * arg = ms[i];
if (is_numeral(arg, a)) {
if (!a.is_zero())
num_consts++;
continue;
}
if (first) {
get_power_product(arg, g);
SASSERT(g.is_int());
first = false;
}
else {
get_power_product(arg, a);
SASSERT(a.is_int());
g = gcd(abs(a), g);
}
if (g.is_one())
return;
}
}
bool arith_rewriter::div_polynomial(expr * t, numeral const & g, const_treatment ct, expr_ref & result) {
SASSERT(m_util.is_int(t));
SASSERT(!g.is_one());
unsigned sz;
expr * const * ms = get_monomials(t, sz);
expr_ref_buffer new_args(m());
numeral a;
for (unsigned i = 0; i < sz; i++) {
expr * arg = ms[i];
if (is_numeral(arg, a)) {
a /= g;
if (!a.is_int()) {
switch (ct) {
case CT_FLOOR:
a = floor(a);
break;
case CT_CEIL:
a = ceil(a);
break;
case CT_FALSE:
return false;
}
}
if (!a.is_zero())
new_args.push_back(m_util.mk_numeral(a, true));
continue;
}
expr * pp = get_power_product(arg, a);
a /= g;
SASSERT(a.is_int());
if (!a.is_zero()) {
if (a.is_one())
new_args.push_back(pp);
else
new_args.push_back(m_util.mk_mul(m_util.mk_numeral(a, true), pp));
}
}
switch (new_args.size()) {
case 0: result = m_util.mk_numeral(numeral(0), true); return true;
case 1: result = new_args[0]; return true;
default: result = m_util.mk_add(new_args.size(), new_args.c_ptr()); return true;
}
}
bool arith_rewriter::is_bound(expr * arg1, expr * arg2, op_kind kind, expr_ref & result) {
numeral c;
if (!is_add(arg1) && is_numeral(arg2, c)) {
numeral a;
bool r = false;
expr * pp = get_power_product(arg1, a);
if (a.is_neg()) {
a.neg();
c.neg();
kind = inv(kind);
r = true;
}
if (!a.is_one())
r = true;
if (!r)
return false;
c /= a;
bool is_int = m_util.is_int(arg1);
if (is_int && !c.is_int()) {
switch (kind) {
case LE: c = floor(c); break;
case GE: c = ceil(c); break;
case EQ: result = m().mk_false(); return true;
}
}
expr * k = m_util.mk_numeral(c, is_int);
switch (kind) {
case LE: result = m_util.mk_le(pp, k); return true;
case GE: result = m_util.mk_ge(pp, k); return true;
case EQ: result = m_util.mk_eq(pp, k); return true;
}
}
return false;
}
bool arith_rewriter::elim_to_real_var(expr * var, expr_ref & new_var) {
numeral val;
if (m_util.is_numeral(var, val)) {
if (!val.is_int())
return false;
new_var = m_util.mk_numeral(val, true);
return true;
}
else if (m_util.is_to_real(var)) {
new_var = to_app(var)->get_arg(0);
return true;
}
return false;
}
bool arith_rewriter::elim_to_real_mon(expr * monomial, expr_ref & new_monomial) {
if (m_util.is_mul(monomial)) {
expr_ref_buffer new_vars(m());
expr_ref new_var(m());
unsigned num = to_app(monomial)->get_num_args();
for (unsigned i = 0; i < num; i++) {
if (!elim_to_real_var(to_app(monomial)->get_arg(i), new_var))
return false;
new_vars.push_back(new_var);
}
new_monomial = m_util.mk_mul(new_vars.size(), new_vars.c_ptr());
return true;
}
else {
return elim_to_real_var(monomial, new_monomial);
}
}
bool arith_rewriter::elim_to_real_pol(expr * p, expr_ref & new_p) {
if (m_util.is_add(p)) {
expr_ref_buffer new_monomials(m());
expr_ref new_monomial(m());
unsigned num = to_app(p)->get_num_args();
for (unsigned i = 0; i < num; i++) {
if (!elim_to_real_mon(to_app(p)->get_arg(i), new_monomial))
return false;
new_monomials.push_back(new_monomial);
}
new_p = m_util.mk_add(new_monomials.size(), new_monomials.c_ptr());
return true;
}
else {
return elim_to_real_mon(p, new_p);
}
}
bool arith_rewriter::elim_to_real(expr * arg1, expr * arg2, expr_ref & new_arg1, expr_ref & new_arg2) {
if (!m_util.is_real(arg1))
return false;
return elim_to_real_pol(arg1, new_arg1) && elim_to_real_pol(arg2, new_arg2);
}
bool arith_rewriter::is_reduce_power_target(expr * arg, bool is_eq) {
unsigned sz;
expr * const * args;
if (m_util.is_mul(arg)) {
sz = to_app(arg)->get_num_args();
args = to_app(arg)->get_args();
}
else {
sz = 1;
args = &arg;
}
for (unsigned i = 0; i < sz; i++) {
expr * arg = args[i];
if (m_util.is_power(arg)) {
rational k;
if (m_util.is_numeral(to_app(arg)->get_arg(1), k) && k.is_int() && ((is_eq && k > rational(1)) || (!is_eq && k > rational(2))))
return true;
}
}
return false;
}
expr * arith_rewriter::reduce_power(expr * arg, bool is_eq) {
if (is_zero(arg))
return arg;
unsigned sz;
expr * const * args;
if (m_util.is_mul(arg)) {
sz = to_app(arg)->get_num_args();
args = to_app(arg)->get_args();
}
else {
sz = 1;
args = &arg;
}
ptr_buffer<expr> new_args;
rational k;
for (unsigned i = 0; i < sz; i++) {
expr * arg = args[i];
if (m_util.is_power(arg) && m_util.is_numeral(to_app(arg)->get_arg(1), k) && k.is_int() && ((is_eq && k > rational(1)) || (!is_eq && k > rational(2)))) {
if (is_eq || !k.is_even())
new_args.push_back(to_app(arg)->get_arg(0));
else
new_args.push_back(m_util.mk_power(to_app(arg)->get_arg(0), m_util.mk_numeral(rational(2), m_util.is_int(arg))));
}
else {
new_args.push_back(arg);
}
}
SASSERT(new_args.size() >= 1);
if (new_args.size() == 1)
return new_args[0];
else
return m_util.mk_mul(new_args.size(), new_args.c_ptr());
}
br_status arith_rewriter::reduce_power(expr * arg1, expr * arg2, op_kind kind, expr_ref & result) {
expr * new_arg1 = reduce_power(arg1, kind == EQ);
expr * new_arg2 = reduce_power(arg2, kind == EQ);
switch (kind) {
case LE: result = m_util.mk_le(new_arg1, new_arg2); return BR_REWRITE1;
case GE: result = m_util.mk_ge(new_arg1, new_arg2); return BR_REWRITE1;
default: result = m().mk_eq(new_arg1, new_arg2); return BR_REWRITE1;
}
}
br_status arith_rewriter::mk_le_ge_eq_core(expr * arg1, expr * arg2, op_kind kind, expr_ref & result) {
expr_ref new_arg1(m());
expr_ref new_arg2(m());
if ((is_zero(arg1) && is_reduce_power_target(arg2, kind == EQ)) ||
(is_zero(arg2) && is_reduce_power_target(arg1, kind == EQ)))
return reduce_power(arg1, arg2, kind, result);
CTRACE("elim_to_real", m_elim_to_real, tout << "after_elim_to_real\n" << mk_ismt2_pp(arg1, m()) << "\n" << mk_ismt2_pp(arg2, m()) << "\n";);
br_status st = cancel_monomials(arg1, arg2, m_arith_lhs, new_arg1, new_arg2);
TRACE("mk_le_bug", tout << "st: " << st << "\n";);
if (st != BR_FAILED) {
arg1 = new_arg1;
arg2 = new_arg2;
}
expr_ref new_new_arg1(m());
expr_ref new_new_arg2(m());
if (m_elim_to_real && elim_to_real(arg1, arg2, new_new_arg1, new_new_arg2)) {
arg1 = new_new_arg1;
arg2 = new_new_arg2;
if (st == BR_FAILED)
st = BR_DONE;
}
numeral a1, a2;
if (is_numeral(arg1, a1) && is_numeral(arg2, a2)) {
switch (kind) {
case LE: result = a1 <= a2 ? m().mk_true() : m().mk_false(); return BR_DONE;
case GE: result = a1 >= a2 ? m().mk_true() : m().mk_false(); return BR_DONE;
default: result = a1 == a2 ? m().mk_true() : m().mk_false(); return BR_DONE;
}
}
#define ANUM_LE_GE_EQ() { \
switch (kind) { \
case LE: result = am.le(v1, v2) ? m().mk_true() : m().mk_false(); return BR_DONE; \
case GE: result = am.ge(v1, v2) ? m().mk_true() : m().mk_false(); return BR_DONE; \
default: result = am.eq(v1, v2) ? m().mk_true() : m().mk_false(); return BR_DONE; \
} \
}
if (m_anum_simp) {
if (is_numeral(arg1, a1) && m_util.is_irrational_algebraic_numeral(arg2)) {
anum_manager & am = m_util.am();
scoped_anum v1(am);
am.set(v1, a1.to_mpq());
anum const & v2 = m_util.to_irrational_algebraic_numeral(arg2);
ANUM_LE_GE_EQ();
}
if (m_util.is_irrational_algebraic_numeral(arg1) && is_numeral(arg2, a2)) {
anum_manager & am = m_util.am();
anum const & v1 = m_util.to_irrational_algebraic_numeral(arg1);
scoped_anum v2(am);
am.set(v2, a2.to_mpq());
ANUM_LE_GE_EQ();
}
if (m_util.is_irrational_algebraic_numeral(arg1) && m_util.is_irrational_algebraic_numeral(arg2)) {
anum_manager & am = m_util.am();
anum const & v1 = m_util.to_irrational_algebraic_numeral(arg1);
anum const & v2 = m_util.to_irrational_algebraic_numeral(arg2);
ANUM_LE_GE_EQ();
}
}
if (is_bound(arg1, arg2, kind, result))
return BR_DONE;
if (is_bound(arg2, arg1, inv(kind), result))
return BR_DONE;
bool is_int = m_util.is_int(arg1);
if (is_int && m_gcd_rounding) {
bool first = true;
numeral g;
unsigned num_consts = 0;
get_coeffs_gcd(arg1, g, first, num_consts);
TRACE("arith_rewriter_gcd", tout << "[step1] g: " << g << ", num_consts: " << num_consts << "\n";);
if ((first || !g.is_one()) && num_consts <= 1)
get_coeffs_gcd(arg2, g, first, num_consts);
TRACE("arith_rewriter_gcd", tout << "[step2] g: " << g << ", num_consts: " << num_consts << "\n";);
if (!first && !g.is_one() && num_consts <= 1) {
bool is_sat = div_polynomial(arg1, g, (kind == LE ? CT_CEIL : (kind == GE ? CT_FLOOR : CT_FALSE)), new_arg1);
if (!is_sat) {
result = m().mk_false();
return BR_DONE;
}
is_sat = div_polynomial(arg2, g, (kind == LE ? CT_FLOOR : (kind == GE ? CT_CEIL : CT_FALSE)), new_arg2);
if (!is_sat) {
result = m().mk_false();
return BR_DONE;
}
arg1 = new_arg1.get();
arg2 = new_arg2.get();
st = BR_DONE;
}
}
if (st != BR_FAILED) {
switch (kind) {
case LE: result = m_util.mk_le(arg1, arg2); return BR_DONE;
case GE: result = m_util.mk_ge(arg1, arg2); return BR_DONE;
default: result = m().mk_eq(arg1, arg2); return BR_DONE;
}
}
return BR_FAILED;
}
br_status arith_rewriter::mk_le_core(expr * arg1, expr * arg2, expr_ref & result) {
return mk_le_ge_eq_core(arg1, arg2, LE, result);
}
br_status arith_rewriter::mk_lt_core(expr * arg1, expr * arg2, expr_ref & result) {
result = m().mk_not(m_util.mk_le(arg2, arg1));
return BR_REWRITE2;
}
br_status arith_rewriter::mk_ge_core(expr * arg1, expr * arg2, expr_ref & result) {
return mk_le_ge_eq_core(arg1, arg2, GE, result);
}
br_status arith_rewriter::mk_gt_core(expr * arg1, expr * arg2, expr_ref & result) {
result = m().mk_not(m_util.mk_le(arg1, arg2));
return BR_REWRITE2;
}
br_status arith_rewriter::mk_eq_core(expr * arg1, expr * arg2, expr_ref & result) {
if (m_eq2ineq) {
result = m().mk_and(m_util.mk_le(arg1, arg2), m_util.mk_ge(arg1, arg2));
return BR_REWRITE2;
}
return mk_le_ge_eq_core(arg1, arg2, EQ, result);
}
bool arith_rewriter::is_anum_simp_target(unsigned num_args, expr * const * args) {
if (!m_anum_simp)
return false;
unsigned num_irrat = 0;
unsigned num_rat = 0;
for (unsigned i = 0; i < num_args; i++) {
if (m_util.is_numeral(args[i])) {
num_rat++;
if (num_irrat > 0)
return true;
}
if (m_util.is_irrational_algebraic_numeral(args[i]) &&
m_util.am().degree(m_util.to_irrational_algebraic_numeral(args[i])) <= m_max_degree) {
num_irrat++;
if (num_irrat > 1 || num_rat > 0)
return true;
}
}
return false;
}
br_status arith_rewriter::mk_add_core(unsigned num_args, expr * const * args, expr_ref & result) {
if (is_anum_simp_target(num_args, args)) {
expr_ref_buffer new_args(m());
anum_manager & am = m_util.am();
scoped_anum r(am);
scoped_anum arg(am);
rational rarg;
am.set(r, 0);
for (unsigned i = 0; i < num_args; i ++) {
unsigned d = am.degree(r);
if (d > 1 && d > m_max_degree) {
new_args.push_back(m_util.mk_numeral(r, false));
am.set(r, 0);
}
if (m_util.is_numeral(args[i], rarg)) {
am.set(arg, rarg.to_mpq());
am.add(r, arg, r);
continue;
}
if (m_util.is_irrational_algebraic_numeral(args[i])) {
anum const & irarg = m_util.to_irrational_algebraic_numeral(args[i]);
if (am.degree(irarg) <= m_max_degree) {
am.add(r, irarg, r);
continue;
}
}
new_args.push_back(args[i]);
}
if (new_args.empty()) {
result = m_util.mk_numeral(r, false);
return BR_DONE;
}
new_args.push_back(m_util.mk_numeral(r, false));
br_status st = poly_rewriter<arith_rewriter_core>::mk_add_core(new_args.size(), new_args.c_ptr(), result);
if (st == BR_FAILED) {
result = m().mk_app(get_fid(), OP_ADD, new_args.size(), new_args.c_ptr());
return BR_DONE;
}
return st;
}
else {
return poly_rewriter<arith_rewriter_core>::mk_add_core(num_args, args, result);
}
}
br_status arith_rewriter::mk_mul_core(unsigned num_args, expr * const * args, expr_ref & result) {
if (is_anum_simp_target(num_args, args)) {
expr_ref_buffer new_args(m());
anum_manager & am = m_util.am();
scoped_anum r(am);
scoped_anum arg(am);
rational rarg;
am.set(r, 1);
for (unsigned i = 0; i < num_args; i ++) {
unsigned d = am.degree(r);
if (d > 1 && d > m_max_degree) {
new_args.push_back(m_util.mk_numeral(r, false));
am.set(r, 1);
}
if (m_util.is_numeral(args[i], rarg)) {
am.set(arg, rarg.to_mpq());
am.mul(r, arg, r);
continue;
}
if (m_util.is_irrational_algebraic_numeral(args[i])) {
anum const & irarg = m_util.to_irrational_algebraic_numeral(args[i]);
if (am.degree(irarg) <= m_max_degree) {
am.mul(r, irarg, r);
continue;
}
}
new_args.push_back(args[i]);
}
if (new_args.empty()) {
result = m_util.mk_numeral(r, false);
return BR_DONE;
}
new_args.push_back(m_util.mk_numeral(r, false));
br_status st = poly_rewriter<arith_rewriter_core>::mk_mul_core(new_args.size(), new_args.c_ptr(), result);
if (st == BR_FAILED) {
result = m().mk_app(get_fid(), OP_MUL, new_args.size(), new_args.c_ptr());
return BR_DONE;
}
return st;
}
else {
return poly_rewriter<arith_rewriter_core>::mk_mul_core(num_args, args, result);
}
}
br_status arith_rewriter::mk_div_irrat_rat(expr * arg1, expr * arg2, expr_ref & result) {
SASSERT(m_util.is_real(arg1));
SASSERT(m_util.is_irrational_algebraic_numeral(arg1));
SASSERT(m_util.is_numeral(arg2));
anum_manager & am = m_util.am();
anum const & val1 = m_util.to_irrational_algebraic_numeral(arg1);
rational rval2;
VERIFY(m_util.is_numeral(arg2, rval2));
if (rval2.is_zero())
return BR_FAILED;
scoped_anum val2(am);
am.set(val2, rval2.to_mpq());
scoped_anum r(am);
am.div(val1, val2, r);
result = m_util.mk_numeral(r, false);
return BR_DONE;
}
br_status arith_rewriter::mk_div_rat_irrat(expr * arg1, expr * arg2, expr_ref & result) {
SASSERT(m_util.is_real(arg1));
SASSERT(m_util.is_numeral(arg1));
SASSERT(m_util.is_irrational_algebraic_numeral(arg2));
anum_manager & am = m_util.am();
rational rval1;
VERIFY(m_util.is_numeral(arg1, rval1));
scoped_anum val1(am);
am.set(val1, rval1.to_mpq());
anum const & val2 = m_util.to_irrational_algebraic_numeral(arg2);
scoped_anum r(am);
am.div(val1, val2, r);
result = m_util.mk_numeral(r, false);
return BR_DONE;
}
br_status arith_rewriter::mk_div_irrat_irrat(expr * arg1, expr * arg2, expr_ref & result) {
SASSERT(m_util.is_real(arg1));
SASSERT(m_util.is_irrational_algebraic_numeral(arg1));
SASSERT(m_util.is_irrational_algebraic_numeral(arg2));
anum_manager & am = m_util.am();
anum const & val1 = m_util.to_irrational_algebraic_numeral(arg1);
if (am.degree(val1) > m_max_degree)
return BR_FAILED;
anum const & val2 = m_util.to_irrational_algebraic_numeral(arg2);
if (am.degree(val2) > m_max_degree)
return BR_FAILED;
scoped_anum r(am);
am.div(val1, val2, r);
result = m_util.mk_numeral(r, false);
return BR_DONE;
}
br_status arith_rewriter::mk_div_core(expr * arg1, expr * arg2, expr_ref & result) {
if (m_anum_simp) {
if (m_util.is_irrational_algebraic_numeral(arg1) && m_util.is_numeral(arg2))
return mk_div_irrat_rat(arg1, arg2, result);
if (m_util.is_irrational_algebraic_numeral(arg1) && m_util.is_irrational_algebraic_numeral(arg2))
return mk_div_irrat_irrat(arg1, arg2, result);
if (m_util.is_irrational_algebraic_numeral(arg2) && m_util.is_numeral(arg1))
return mk_div_rat_irrat(arg1, arg2, result);
}
set_curr_sort(m().get_sort(arg1));
numeral v1, v2;
bool is_int;
if (m_util.is_numeral(arg2, v2, is_int) && !v2.is_zero()) {
SASSERT(!is_int);
if (m_util.is_numeral(arg1, v1, is_int)) {
result = m_util.mk_numeral(v1/v2, false);
return BR_DONE;
}
else {
numeral k(1);
k /= v2;
result = m().mk_app(get_fid(), OP_MUL,
m_util.mk_numeral(k, false),
arg1);
return BR_REWRITE1;
}
}
if (!m_util.is_int(arg1)) {
// (/ (* v1 b) (* v2 d)) --> (* v1/v2 (/ b d))
expr * a, * b, * c, * d;
if (m_util.is_mul(arg1, a, b) && m_util.is_numeral(a, v1)) {
// do nothing arg1 is of the form v1 * b
}
else {
v1 = rational(1);
b = arg1;
}
if (m_util.is_mul(arg2, c, d) && m_util.is_numeral(c, v2)) {
// do nothing arg2 is of the form v2 * d
}
else {
v2 = rational(1);
d = arg2;
}
TRACE("div_bug", tout << "v1: " << v1 << ", v2: " << v2 << "\n";);
if (!v1.is_one() || !v2.is_one()) {
v1 /= v2;
result = m_util.mk_mul(m_util.mk_numeral(v1, false),
m_util.mk_div(b, d));
return BR_REWRITE2;
}
}
return BR_FAILED;
}
br_status arith_rewriter::mk_idiv_core(expr * arg1, expr * arg2, expr_ref & result) {
set_curr_sort(m().get_sort(arg1));
numeral v1, v2;
bool is_int;
if (m_util.is_numeral(arg1, v1, is_int) && m_util.is_numeral(arg2, v2, is_int) && !v2.is_zero()) {
result = m_util.mk_numeral(div(v1, v2), is_int);
return BR_DONE;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_mod_core(expr * arg1, expr * arg2, expr_ref & result) {
set_curr_sort(m().get_sort(arg1));
numeral v1, v2;
bool is_int;
if (m_util.is_numeral(arg1, v1, is_int) && m_util.is_numeral(arg2, v2, is_int) && !v2.is_zero()) {
result = m_util.mk_numeral(mod(v1, v2), is_int);
return BR_DONE;
}
if (m_util.is_numeral(arg2, v2, is_int) && is_int && v2.is_one()) {
result = m_util.mk_numeral(numeral(0), true);
return BR_DONE;
}
// mod is idempotent on non-zero modulus.
expr* t1, *t2;
if (m_util.is_mod(arg1, t1, t2) && t2 == arg2 && m_util.is_numeral(arg2, v2, is_int) && is_int && !v2.is_zero()) {
result = arg1;
return BR_DONE;
}
// propagate mod inside only if not all arguments are not already mod.
if (m_util.is_numeral(arg2, v2, is_int) && is_int && v2.is_pos() && (is_add(arg1) || is_mul(arg1))) {
TRACE("mod_bug", tout << "mk_mod:\n" << mk_ismt2_pp(arg1, m()) << "\n" << mk_ismt2_pp(arg2, m()) << "\n";);
unsigned num_args = to_app(arg1)->get_num_args();
unsigned i;
rational arg_v;
for (i = 0; i < num_args; i++) {
expr * arg = to_app(arg1)->get_arg(i);
if (m_util.is_mod(arg))
continue;
if (m_util.is_numeral(arg, arg_v) && mod(arg_v, v2) == arg_v)
continue;
// found target for rewriting
break;
}
TRACE("mod_bug", tout << "mk_mod target: " << i << "\n";);
if (i == num_args)
return BR_FAILED; // did not find any target for applying simplification
ptr_buffer<expr> new_args;
for (unsigned i = 0; i < num_args; i++)
new_args.push_back(m_util.mk_mod(to_app(arg1)->get_arg(i), arg2));
result = m_util.mk_mod(m().mk_app(to_app(arg1)->get_decl(), new_args.size(), new_args.c_ptr()), arg2);
TRACE("mod_bug", tout << "mk_mod result: " << mk_ismt2_pp(result, m()) << "\n";);
return BR_REWRITE3;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_rem_core(expr * arg1, expr * arg2, expr_ref & result) {
set_curr_sort(m().get_sort(arg1));
numeral v1, v2;
bool is_int;
if (m_util.is_numeral(arg1, v1, is_int) && m_util.is_numeral(arg2, v2, is_int) && !v2.is_zero()) {
numeral m = mod(v1, v2);
//
// rem(v1,v2) = if v2 >= 0 then mod(v1,v2) else -mod(v1,v2)
//
if (v2.is_neg()) {
m.neg();
}
result = m_util.mk_numeral(m, is_int);
return BR_DONE;
}
else if (m_util.is_numeral(arg2, v2, is_int) && is_int && v2.is_one()) {
result = m_util.mk_numeral(numeral(0), true);
return BR_DONE;
}
else if (m_util.is_numeral(arg2, v2, is_int) && is_int && !v2.is_zero()) {
if (is_add(arg1) || is_mul(arg1)) {
ptr_buffer<expr> new_args;
unsigned num_args = to_app(arg1)->get_num_args();
for (unsigned i = 0; i < num_args; i++)
new_args.push_back(m_util.mk_rem(to_app(arg1)->get_arg(i), arg2));
result = m().mk_app(to_app(arg1)->get_decl(), new_args.size(), new_args.c_ptr());
return BR_REWRITE2;
}
else {
if (v2.is_neg()) {
result = m_util.mk_uminus(m_util.mk_mod(arg1, arg2));
return BR_REWRITE2;
}
else {
result = m_util.mk_mod(arg1, arg2);
return BR_REWRITE1;
}
}
}
else if (m_elim_rem) {
expr * mod = m_util.mk_mod(arg1, arg2);
result = m().mk_ite(m_util.mk_ge(arg2, m_util.mk_numeral(rational(0), true)),
mod,
m_util.mk_uminus(mod));
TRACE("elim_rem", tout << "result: " << mk_ismt2_pp(result, m()) << "\n";);
return BR_REWRITE3;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_power_core(expr * arg1, expr * arg2, expr_ref & result) {
numeral x, y;
bool is_num_x = m_util.is_numeral(arg1, x);
bool is_num_y = m_util.is_numeral(arg2, y);
bool is_int_sort = m_util.is_int(arg1);
if ((is_num_x && x.is_one()) ||
(is_num_y && y.is_one())) {
result = arg1;
return BR_DONE;
}
if (is_num_x && is_num_y) {
if (x.is_zero() && y.is_zero())
return BR_FAILED;
if (y.is_zero()) {
result = m_util.mk_numeral(rational(1), m().get_sort(arg1));
return BR_DONE;
}
if (x.is_zero()) {
result = arg1;
return BR_DONE;
}
if (y.is_unsigned() && y.get_unsigned() <= m_max_degree) {
x = power(x, y.get_unsigned());
result = m_util.mk_numeral(x, m().get_sort(arg1));
return BR_DONE;
}
if (!is_int_sort && (-y).is_unsigned() && (-y).get_unsigned() <= m_max_degree) {
x = power(rational(1)/x, (-y).get_unsigned());
result = m_util.mk_numeral(x, m().get_sort(arg1));
return BR_DONE;
}
}
if (m_util.is_power(arg1) && is_num_y && y.is_int() && !y.is_zero()) {
// (^ (^ t y2) y) --> (^ t (* y2 y)) If y2 > 0 && y != 0 && y and y2 are integers
rational y2;
if (m_util.is_numeral(to_app(arg1)->get_arg(1), y2) && y2.is_int() && y2.is_pos()) {
result = m_util.mk_power(to_app(arg1)->get_arg(0), m_util.mk_numeral(y*y2, is_int_sort));
return BR_REWRITE1;
}
}
if (!is_int_sort && is_num_y && y.is_neg()) {
// (^ t -k) --> (^ (/ 1 t) k)
result = m_util.mk_power(m_util.mk_div(m_util.mk_numeral(rational(1), false), arg1),
m_util.mk_numeral(-y, false));
return BR_REWRITE2;
}
if (!is_int_sort && is_num_y && !y.is_int() && !numerator(y).is_one()) {
// (^ t (/ p q)) --> (^ (^ t (/ 1 q)) p)
result = m_util.mk_power(m_util.mk_power(arg1, m_util.mk_numeral(rational(1)/denominator(y), false)),
m_util.mk_numeral(numerator(y), false));
return BR_REWRITE2;
}
if ((m_expand_power || (m_som && is_app(arg1) && to_app(arg1)->get_family_id() == get_fid())) &&
is_num_y && y.is_unsigned() && 1 < y.get_unsigned() && y.get_unsigned() <= m_max_degree) {
ptr_buffer<expr> args;
unsigned k = y.get_unsigned();
for (unsigned i = 0; i < k; i++) {
args.push_back(arg1);
}
result = m_util.mk_mul(args.size(), args.c_ptr());
return BR_REWRITE1;
}
if (!is_num_y)
return BR_FAILED;
bool is_irrat_x = m_util.is_irrational_algebraic_numeral(arg1);
if (!is_num_x && !is_irrat_x)
return BR_FAILED;
rational num_y = numerator(y);
rational den_y = denominator(y);
bool is_neg_y = false;
if (num_y.is_neg()) {
num_y.neg();
is_neg_y = true;
}
SASSERT(num_y.is_pos());
SASSERT(den_y.is_pos());
if (is_neg_y && is_int_sort)
return BR_FAILED;
if (!num_y.is_unsigned() || !den_y.is_unsigned())
return BR_FAILED;
unsigned u_num_y = num_y.get_unsigned();
unsigned u_den_y = den_y.get_unsigned();
if (u_num_y > m_max_degree || u_den_y > m_max_degree)
return BR_FAILED;
if (is_num_x) {
rational xk, r;
xk = power(x, u_num_y);
if (xk.root(u_den_y, r)) {
if (is_neg_y)
r = rational(1)/r;
result = m_util.mk_numeral(r, m().get_sort(arg1));
return BR_DONE;
}
if (m_anum_simp) {
anum_manager & am = m_util.am();
scoped_anum r(am);
am.set(r, xk.to_mpq());
am.root(r, u_den_y, r);
if (is_neg_y)
am.inv(r);
result = m_util.mk_numeral(r, false);
return BR_DONE;
}
return BR_FAILED;
}
SASSERT(is_irrat_x);
if (!m_anum_simp)
return BR_FAILED;
anum const & val = m_util.to_irrational_algebraic_numeral(arg1);
anum_manager & am = m_util.am();
if (am.degree(val) > m_max_degree)
return BR_FAILED;
scoped_anum r(am);
am.power(val, u_num_y, r);
am.root(r, u_den_y, r);
if (is_neg_y)
am.inv(r);
result = m_util.mk_numeral(r, false);
return BR_DONE;
}
br_status arith_rewriter::mk_to_int_core(expr * arg, expr_ref & result) {
numeral a;
if (m_util.is_numeral(arg, a)) {
result = m_util.mk_numeral(floor(a), true);
return BR_DONE;
}
else if (m_util.is_to_real(arg)) {
result = to_app(arg)->get_arg(0);
return BR_DONE;
}
else {
if (m_util.is_add(arg) || m_util.is_mul(arg) || m_util.is_power(arg)) {
// Try to apply simplifications such as:
// (to_int (+ 1.0 (to_real x))) --> (+ 1 x)
// if all arguments of arg are
// - integer numerals, OR
// - to_real applications
// then, to_int can be eliminated
unsigned num_args = to_app(arg)->get_num_args();
unsigned i = 0;
for (; i < num_args; i++) {
expr * c = to_app(arg)->get_arg(i);
if (m_util.is_numeral(c, a) && a.is_int())
continue;
if (m_util.is_to_real(c))
continue;
break; // failed
}
if (i == num_args) {
// simplification can be applied
expr_ref_buffer new_args(m());
for (i = 0; i < num_args; i++) {
expr * c = to_app(arg)->get_arg(i);
if (m_util.is_numeral(c, a) && a.is_int()) {
new_args.push_back(m_util.mk_numeral(a, true));
}
else {
SASSERT(m_util.is_to_real(c));
new_args.push_back(to_app(c)->get_arg(0));
}
}
SASSERT(num_args == new_args.size());
result = m().mk_app(get_fid(), to_app(arg)->get_decl()->get_decl_kind(), new_args.size(), new_args.c_ptr());
return BR_REWRITE1;
}
}
return BR_FAILED;
}
}
br_status arith_rewriter::mk_to_real_core(expr * arg, expr_ref & result) {
numeral a;
if (m_util.is_numeral(arg, a)) {
result = m_util.mk_numeral(a, false);
return BR_DONE;
}
#if 0
// The following rewriting rule is not correct.
// It is used only for making experiments.
if (m_util.is_to_int(arg)) {
result = to_app(arg)->get_arg(0);
return BR_DONE;
}
#endif
// push to_real over OP_ADD, OP_MUL
if (m_push_to_real) {
if (m_util.is_add(arg) || m_util.is_mul(arg)) {
ptr_buffer<expr> new_args;
unsigned num = to_app(arg)->get_num_args();
for (unsigned i = 0; i < num; i++) {
new_args.push_back(m_util.mk_to_real(to_app(arg)->get_arg(i)));
}
if (m_util.is_add(arg))
result = m().mk_app(get_fid(), OP_ADD, new_args.size(), new_args.c_ptr());
else
result = m().mk_app(get_fid(), OP_MUL, new_args.size(), new_args.c_ptr());
return BR_REWRITE2;
}
}
return BR_FAILED;
}
br_status arith_rewriter::mk_is_int(expr * arg, expr_ref & result) {
numeral a;
if (m_util.is_numeral(arg, a)) {
result = a.is_int() ? m().mk_true() : m().mk_false();
return BR_DONE;
}
else if (m_util.is_to_real(arg)) {
result = m().mk_true();
return BR_DONE;
}
else {
result = m().mk_eq(m().mk_app(get_fid(), OP_TO_REAL,
m().mk_app(get_fid(), OP_TO_INT, arg)),
arg);
return BR_REWRITE3;
}
}
void arith_rewriter::set_cancel(bool f) {
m_util.set_cancel(f);
}
// Return true if t is of the form c*Pi where c is a numeral.
// Store c into k
bool arith_rewriter::is_pi_multiple(expr * t, rational & k) {
if (m_util.is_pi(t)) {
k = rational(1);
return true;
}
expr * a, * b;
return m_util.is_mul(t, a, b) && m_util.is_pi(b) && m_util.is_numeral(a, k);
}
// Return true if t is of the form (+ s c*Pi) where c is a numeral.
// Store c into k, and c*Pi into m.
bool arith_rewriter::is_pi_offset(expr * t, rational & k, expr * & m) {
if (m_util.is_add(t)) {
unsigned num = to_app(t)->get_num_args();
for (unsigned i = 0; i < num; i++) {
expr * arg = to_app(t)->get_arg(i);
if (is_pi_multiple(arg, k)) {
m = arg;
return true;
}
}
}
return false;
}
// Return true if t is of the form 2*pi*to_real(s).
bool arith_rewriter::is_2_pi_integer(expr * t) {
expr * a, * m, * b, * c;
rational k;
return
m_util.is_mul(t, a, m) &&
m_util.is_numeral(a, k) &&
k.is_int() &&
mod(k, rational(2)).is_zero() &&
m_util.is_mul(m, b, c) &&
((m_util.is_pi(b) && m_util.is_to_real(c)) || (m_util.is_to_real(b) && m_util.is_pi(c)));
}
// Return true if t is of the form s + 2*pi*to_real(s).
// Store 2*pi*to_real(s) into m.
bool arith_rewriter::is_2_pi_integer_offset(expr * t, expr * & m) {
if (m_util.is_add(t)) {
unsigned num = to_app(t)->get_num_args();
for (unsigned i = 0; i < num; i++) {
expr * arg = to_app(t)->get_arg(i);
if (is_2_pi_integer(arg)) {
m = arg;
return true;
}
}
}
return false;
}
// Return true if t is of the form pi*to_real(s).
bool arith_rewriter::is_pi_integer(expr * t) {
expr * a, * b;
if (m_util.is_mul(t, a, b)) {
rational k;
if (m_util.is_numeral(a, k)) {
if (!k.is_int())
return false;
expr * c, * d;
if (!m_util.is_mul(b, c, d))
return false;
a = c;
b = d;
}
TRACE("tan", tout << "is_pi_integer " << mk_ismt2_pp(t, m()) << "\n";
tout << "a: " << mk_ismt2_pp(a, m()) << "\n";
tout << "b: " << mk_ismt2_pp(b, m()) << "\n";);
return
(m_util.is_pi(a) && m_util.is_to_real(b)) ||
(m_util.is_to_real(a) && m_util.is_pi(b));
}
return false;
}
// Return true if t is of the form s + pi*to_real(s).
// Store 2*pi*to_real(s) into m.
bool arith_rewriter::is_pi_integer_offset(expr * t, expr * & m) {
if (m_util.is_add(t)) {
unsigned num = to_app(t)->get_num_args();
for (unsigned i = 0; i < num; i++) {
expr * arg = to_app(t)->get_arg(i);
if (is_pi_integer(arg)) {
m = arg;
return true;
}
}
}
return false;
}
app * arith_rewriter::mk_sqrt(rational const & k) {
return m_util.mk_power(m_util.mk_numeral(k, false), m_util.mk_numeral(rational(1, 2), false));
}
// Return a constant representing sin(k * pi).
// Return 0 if failed.
expr * arith_rewriter::mk_sin_value(rational const & k) {
rational k_prime = mod(floor(k), rational(2)) + k - floor(k);
TRACE("sine", tout << "k: " << k << ", k_prime: " << k_prime << "\n";);
SASSERT(k_prime >= rational(0) && k_prime < rational(2));
bool neg = false;
if (k_prime >= rational(1)) {
neg = true;
k_prime = k_prime - rational(1);
}
SASSERT(k_prime >= rational(0) && k_prime < rational(1));
if (k_prime.is_zero() || k_prime.is_one()) {
// sin(0) == sin(pi) == 0
return m_util.mk_numeral(rational(0), false);
}
if (k_prime == rational(1, 2)) {
// sin(pi/2) == 1, sin(3/2 pi) == -1
return m_util.mk_numeral(rational(neg ? -1 : 1), false);
}
if (k_prime == rational(1, 6) || k_prime == rational(5, 6)) {
// sin(pi/6) == sin(5/6 pi) == 1/2
// sin(7 pi/6) == sin(11/6 pi) == -1/2
return m_util.mk_numeral(rational(neg ? -1 : 1, 2), false);
}
if (k_prime == rational(1, 4) || k_prime == rational(3, 4)) {
// sin(pi/4) == sin(3/4 pi) == Sqrt(1/2)
// sin(5/4 pi) == sin(7/4 pi) == - Sqrt(1/2)
expr * result = mk_sqrt(rational(1, 2));
return neg ? m_util.mk_uminus(result) : result;
}
if (k_prime == rational(1, 3) || k_prime == rational(2, 3)) {
// sin(pi/3) == sin(2/3 pi) == Sqrt(3)/2
// sin(4/3 pi) == sin(5/3 pi) == - Sqrt(3)/2
expr * result = m_util.mk_div(mk_sqrt(rational(3)), m_util.mk_numeral(rational(2), false));
return neg ? m_util.mk_uminus(result) : result;
}
if (k_prime == rational(1, 12) || k_prime == rational(11, 12)) {
// sin(1/12 pi) == sin(11/12 pi) == [sqrt(6) - sqrt(2)]/4
// sin(13/12 pi) == sin(23/12 pi) == -[sqrt(6) - sqrt(2)]/4
expr * result = m_util.mk_div(m_util.mk_sub(mk_sqrt(rational(6)), mk_sqrt(rational(2))), m_util.mk_numeral(rational(4), false));
return neg ? m_util.mk_uminus(result) : result;
}
if (k_prime == rational(5, 12) || k_prime == rational(7, 12)) {
// sin(5/12 pi) == sin(7/12 pi) == [sqrt(6) + sqrt(2)]/4
// sin(17/12 pi) == sin(19/12 pi) == -[sqrt(6) + sqrt(2)]/4
expr * result = m_util.mk_div(m_util.mk_add(mk_sqrt(rational(6)), mk_sqrt(rational(2))), m_util.mk_numeral(rational(4), false));
return neg ? m_util.mk_uminus(result) : result;
}
return 0;
}
br_status arith_rewriter::mk_sin_core(expr * arg, expr_ref & result) {
if (is_app_of(arg, get_fid(), OP_ASIN)) {
// sin(asin(x)) == x
result = to_app(arg)->get_arg(0);
return BR_DONE;
}
rational k;
if (is_numeral(arg, k) && k.is_zero()) {
// sin(0) == 0
result = arg;
return BR_DONE;
}
if (is_pi_multiple(arg, k)) {
result = mk_sin_value(k);
if (result.get() != 0)
return BR_REWRITE_FULL;
}
expr * m;
if (is_pi_offset(arg, k, m)) {
rational k_prime = mod(floor(k), rational(2)) + k - floor(k);
SASSERT(k_prime >= rational(0) && k_prime < rational(2));
if (k_prime.is_zero()) {
// sin(x + 2*n*pi) == sin(x)
result = m_util.mk_sin(m_util.mk_sub(arg, m));
return BR_REWRITE2;
}
if (k_prime == rational(1, 2)) {
// sin(x + pi/2 + 2*n*pi) == cos(x)
result = m_util.mk_cos(m_util.mk_sub(arg, m));
return BR_REWRITE2;
}
if (k_prime.is_one()) {
// sin(x + pi + 2*n*pi) == -sin(x)
result = m_util.mk_uminus(m_util.mk_sin(m_util.mk_sub(arg, m)));
return BR_REWRITE3;
}
if (k_prime == rational(3, 2)) {
// sin(x + 3/2*pi + 2*n*pi) == -cos(x)
result = m_util.mk_uminus(m_util.mk_cos(m_util.mk_sub(arg, m)));
return BR_REWRITE3;
}
}
if (is_2_pi_integer_offset(arg, m)) {
// sin(x + 2*pi*to_real(a)) == sin(x)
result = m_util.mk_sin(m_util.mk_sub(arg, m));
return BR_REWRITE2;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_cos_core(expr * arg, expr_ref & result) {
if (is_app_of(arg, get_fid(), OP_ACOS)) {
// cos(acos(x)) == x
result = to_app(arg)->get_arg(0);
return BR_DONE;
}
rational k;
if (is_numeral(arg, k) && k.is_zero()) {
// cos(0) == 1
result = m_util.mk_numeral(rational(1), false);
return BR_DONE;
}
if (is_pi_multiple(arg, k)) {
k = k + rational(1, 2);
result = mk_sin_value(k);
if (result.get() != 0)
return BR_REWRITE_FULL;
}
expr * m;
if (is_pi_offset(arg, k, m)) {
rational k_prime = mod(floor(k), rational(2)) + k - floor(k);
SASSERT(k_prime >= rational(0) && k_prime < rational(2));
if (k_prime.is_zero()) {
// cos(x + 2*n*pi) == cos(x)
result = m_util.mk_cos(m_util.mk_sub(arg, m));
return BR_REWRITE2;
}
if (k_prime == rational(1, 2)) {
// cos(x + pi/2 + 2*n*pi) == -sin(x)
result = m_util.mk_uminus(m_util.mk_sin(m_util.mk_sub(arg, m)));
return BR_REWRITE3;
}
if (k_prime.is_one()) {
// cos(x + pi + 2*n*pi) == -cos(x)
result = m_util.mk_uminus(m_util.mk_cos(m_util.mk_sub(arg, m)));
return BR_REWRITE3;
}
if (k_prime == rational(3, 2)) {
// cos(x + 3/2*pi + 2*n*pi) == sin(x)
result = m_util.mk_sin(m_util.mk_sub(arg, m));
return BR_REWRITE2;
}
}
if (is_2_pi_integer_offset(arg, m)) {
// cos(x + 2*pi*to_real(a)) == cos(x)
result = m_util.mk_cos(m_util.mk_sub(arg, m));
return BR_REWRITE2;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_tan_core(expr * arg, expr_ref & result) {
if (is_app_of(arg, get_fid(), OP_ATAN)) {
// tan(atan(x)) == x
result = to_app(arg)->get_arg(0);
return BR_DONE;
}
rational k;
if (is_numeral(arg, k) && k.is_zero()) {
// tan(0) == 0
result = arg;
return BR_DONE;
}
if (is_pi_multiple(arg, k)) {
expr_ref n(m()), d(m());
n = mk_sin_value(k);
if (n.get() == 0)
goto end;
if (is_zero(n)) {
result = n;
return BR_DONE;
}
k = k + rational(1, 2);
d = mk_sin_value(k);
SASSERT(d.get() != 0);
if (is_zero(d)) {
goto end;
}
result = m_util.mk_div(n, d);
return BR_REWRITE_FULL;
}
expr * m;
if (is_pi_offset(arg, k, m)) {
rational k_prime = k - floor(k);
SASSERT(k_prime >= rational(0) && k_prime < rational(1));
if (k_prime.is_zero()) {
// tan(x + n*pi) == tan(x)
result = m_util.mk_tan(m_util.mk_sub(arg, m));
return BR_REWRITE2;
}
}
if (is_pi_integer_offset(arg, m)) {
// tan(x + pi*to_real(a)) == tan(x)
result = m_util.mk_tan(m_util.mk_sub(arg, m));
return BR_REWRITE2;
}
end:
if (m_expand_tan) {
result = m_util.mk_div(m_util.mk_sin(arg), m_util.mk_cos(arg));
return BR_REWRITE2;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_asin_core(expr * arg, expr_ref & result) {
// Remark: we assume that ForAll x : asin(-x) == asin(x).
// Mathematica uses this as an axiom. Although asin is an underspecified function for x < -1 or x > 1.
// Actually, in Mathematica, asin(x) is a total function that returns a complex number fo x < -1 or x > 1.
rational k;
if (is_numeral(arg, k)) {
if (k.is_zero()) {
result = arg;
return BR_DONE;
}
if (k < rational(-1)) {
// asin(-2) == -asin(2)
// asin(-3) == -asin(3)
k.neg();
result = m_util.mk_uminus(m_util.mk_asin(m_util.mk_numeral(k, false)));
return BR_REWRITE2;
}
if (k > rational(1))
return BR_FAILED;
bool neg = false;
if (k.is_neg()) {
neg = true;
k.neg();
}
if (k.is_one()) {
// asin(1) == pi/2
// asin(-1) == -pi/2
result = m_util.mk_mul(m_util.mk_numeral(rational(neg ? -1 : 1, 2), false), m_util.mk_pi());
return BR_REWRITE2;
}
if (k == rational(1, 2)) {
// asin(1/2) == pi/6
// asin(-1/2) == -pi/6
result = m_util.mk_mul(m_util.mk_numeral(rational(neg ? -1 : 1, 6), false), m_util.mk_pi());
return BR_REWRITE2;
}
}
expr * t;
if (m_util.is_times_minus_one(arg, t)) {
// See comment above
// asin(-x) ==> -asin(x)
result = m_util.mk_uminus(m_util.mk_asin(t));
return BR_REWRITE2;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_acos_core(expr * arg, expr_ref & result) {
rational k;
if (is_numeral(arg, k)) {
if (k.is_zero()) {
// acos(0) = pi/2
result = m_util.mk_mul(m_util.mk_numeral(rational(1, 2), false), m_util.mk_pi());
return BR_REWRITE2;
}
if (k.is_one()) {
// acos(1) = 0
result = m_util.mk_numeral(rational(0), false);
return BR_DONE;
}
if (k.is_minus_one()) {
// acos(-1) = pi
result = m_util.mk_pi();
return BR_DONE;
}
if (k == rational(1, 2)) {
// acos(1/2) = pi/3
result = m_util.mk_mul(m_util.mk_numeral(rational(1, 3), false), m_util.mk_pi());
return BR_REWRITE2;
}
if (k == rational(-1, 2)) {
// acos(-1/2) = 2/3 pi
result = m_util.mk_mul(m_util.mk_numeral(rational(2, 3), false), m_util.mk_pi());
return BR_REWRITE2;
}
}
return BR_FAILED;
}
br_status arith_rewriter::mk_atan_core(expr * arg, expr_ref & result) {
rational k;
if (is_numeral(arg, k)) {
if (k.is_zero()) {
result = arg;
return BR_DONE;
}
if (k.is_one()) {
// atan(1) == pi/4
result = m_util.mk_mul(m_util.mk_numeral(rational(1, 4), false), m_util.mk_pi());
return BR_REWRITE2;
}
if (k.is_minus_one()) {
// atan(-1) == -pi/4
result = m_util.mk_mul(m_util.mk_numeral(rational(-1, 4), false), m_util.mk_pi());
return BR_REWRITE2;
}
if (k < rational(-1)) {
// atan(-2) == -tan(2)
// atan(-3) == -tan(3)
k.neg();
result = m_util.mk_uminus(m_util.mk_atan(m_util.mk_numeral(k, false)));
return BR_REWRITE2;
}
return BR_FAILED;
}
expr * t;
if (m_util.is_times_minus_one(arg, t)) {
// atan(-x) ==> -atan(x)
result = m_util.mk_uminus(m_util.mk_atan(t));
return BR_REWRITE2;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_sinh_core(expr * arg, expr_ref & result) {
if (is_app_of(arg, get_fid(), OP_ASINH)) {
// sinh(asinh(x)) == x
result = to_app(arg)->get_arg(0);
return BR_DONE;
}
expr * t;
if (m_util.is_times_minus_one(arg, t)) {
// sinh(-t) == -sinh(t)
result = m_util.mk_uminus(m_util.mk_sinh(t));
return BR_REWRITE2;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_cosh_core(expr * arg, expr_ref & result) {
if (is_app_of(arg, get_fid(), OP_ACOSH)) {
// cosh(acosh(x)) == x
result = to_app(arg)->get_arg(0);
return BR_DONE;
}
expr * t;
if (m_util.is_times_minus_one(arg, t)) {
// cosh(-t) == cosh
result = m_util.mk_cosh(t);
return BR_DONE;
}
return BR_FAILED;
}
br_status arith_rewriter::mk_tanh_core(expr * arg, expr_ref & result) {
if (is_app_of(arg, get_fid(), OP_ATANH)) {
// tanh(atanh(x)) == x
result = to_app(arg)->get_arg(0);
return BR_DONE;
}
expr * t;
if (m_util.is_times_minus_one(arg, t)) {
// tanh(-t) == -tanh(t)
result = m_util.mk_uminus(m_util.mk_tanh(t));
return BR_REWRITE2;
}
return BR_FAILED;
}
template class poly_rewriter<arith_rewriter_core>;
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