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PDD operations

This commit is contained in:
Jakob Rath 2022-08-01 14:49:06 +02:00 committed by Nikolaj Bjorner
parent 42233ab5c8
commit de6a0ab1a7
3 changed files with 877 additions and 58 deletions

View file

@ -34,6 +34,7 @@ namespace dd {
s = mod2_e;
m_semantics = s;
m_mod2N = rational::power_of_two(power_of_2);
m_max_value = m_mod2N - 1;
m_power_of_2 = power_of_2;
unsigned_vector l2v;
for (unsigned i = 0; i < num_vars; ++i) l2v.push_back(i);
@ -50,6 +51,7 @@ namespace dd {
void pdd_manager::reset(unsigned_vector const& level2var) {
reset_op_cache();
m_factor_cache.reset();
m_node_table.reset();
m_nodes.reset();
m_free_nodes.reset();
@ -126,7 +128,7 @@ namespace dd {
* Example: 2^4*x + 2 is non-zero for every x.
*/
bool pdd_manager::is_non_zero(PDD p) {
bool pdd_manager::is_never_zero(PDD p) {
if (is_val(p))
return !is_zero(p);
if (m_semantics != mod2N_e)
@ -163,7 +165,11 @@ namespace dd {
return true;
}
pdd pdd_manager::subst_val(pdd const& p, vector<std::pair<unsigned, rational>> const& _s) {
pdd pdd_manager::subst_val(pdd const& p, pdd const& s) {
return pdd(apply(p.root, s.root, pdd_subst_val_op), this);
}
pdd pdd_manager::subst_val0(pdd const& p, vector<std::pair<unsigned, rational>> const& _s) {
typedef std::pair<unsigned, rational> pr;
vector<pr> s(_s);
std::function<bool (pr const&, pr const&)> compare_level =
@ -171,10 +177,16 @@ namespace dd {
std::sort(s.begin(), s.end(), compare_level);
pdd r(one());
for (auto const& q : s)
r = (r*mk_var(q.first)) + q.second;
return pdd(apply(p.root, r.root, pdd_subst_val_op), this);
r = (r * mk_var(q.first)) + q.second;
return subst_val(p, r);
}
pdd pdd_manager::subst_add(pdd const& s, unsigned v, rational const& val) {
pdd v_val = mk_var(v) + val;
return pdd(apply(s.root, v_val.root, pdd_subst_add_op), this);
}
pdd_manager::PDD pdd_manager::apply(PDD arg1, PDD arg2, pdd_op op) {
bool first = true;
SASSERT(well_formed());
@ -216,6 +228,7 @@ namespace dd {
if (is_val(p) && is_val(q)) return imk_val(val(p) - val(q));
if (m_semantics != mod2_e) break;
op = pdd_add_op;
Z3_fallthrough;
case pdd_add_op:
if (is_zero(p)) return q;
if (is_zero(q)) return p;
@ -239,12 +252,16 @@ namespace dd {
break;
case pdd_subst_val_op:
while (!is_val(q) && !is_val(p)) {
if (level(p) == level(q)) break;
if (level(p) < level(q)) q = lo(q);
else p = lo(p);
if (level(p) < level(q)) q = hi(q);
else break;
}
if (is_val(p) || is_val(q)) return p;
break;
case pdd_subst_add_op:
if (is_one(p)) return q;
SASSERT(!is_val(p));
SASSERT(!is_val(q));
break;
default:
UNREACHABLE();
break;
@ -345,7 +362,8 @@ namespace dd {
push(make_node(level_p, lo(n), read(1)));
r = make_node(level_p, bd, read(1));
npop = 7;
} else {
}
else {
push(make_node(level_p, n, ac));
r = make_node(level_p, bd, read(1));
npop = 6;
@ -387,12 +405,33 @@ namespace dd {
case pdd_subst_val_op:
SASSERT(!is_val(p));
SASSERT(!is_val(q));
SASSERT(level_p == level_q);
SASSERT(level_p >= level_q);
push(apply_rec(lo(p), q, pdd_subst_val_op)); // lo := subst(lo(p), s)
push(apply_rec(hi(p), q, pdd_subst_val_op)); // hi := subst(hi(p), s)
push(apply_rec(lo(q), read(1), pdd_mul_op)); // hi := hi*s[var(p)]
r = apply_rec(read(1), read(3), pdd_add_op); // r := hi + lo := subst(lo(p),s) + s[var(p)]*subst(hi(p),s)
npop = 3;
if (level_p > level_q) {
r = make_node(level_p, read(2), read(1));
npop = 2;
}
else {
push(apply_rec(lo(q), read(1), pdd_mul_op)); // hi := hi*s[var(p)]
r = apply_rec(read(1), read(3), pdd_add_op); // r := hi + lo := subst(lo(p),s) + s[var(p)]*subst(hi(p),s)
npop = 3;
}
break;
case pdd_subst_add_op:
SASSERT(!is_val(p));
SASSERT(!is_val(q));
SASSERT(level_p != level_q);
if (level_p < level_q) {
r = make_node(level_q, lo(q), p); // p*hi(q) + lo(q)
npop = 0;
}
else {
push(apply_rec(hi(p), q, pdd_subst_add_op)); // hi := add_subst(hi(p), q)
r = make_node(level_p, lo(p), read(1)); // r := hi*var(p) + lo(p)
npop = 1;
}
break;
default:
r = null_pdd;
@ -405,6 +444,7 @@ namespace dd {
return r;
}
pdd pdd_manager::minus(pdd const& a) {
if (m_semantics == mod2_e) {
return a;
@ -442,6 +482,113 @@ namespace dd {
return r;
}
/**
* Divide PDD by a constant value.
*
* IMPORTANT: Performs regular numerical division.
* For semantics 'mod2N_e', this means that 'c' must be an integer
* and all coefficients of 'a' must be divisible by 'c'.
*
* NOTE: Why do we not just use 'mul(a, inv(c))' instead?
* In case of semantics 'mod2N_e', an invariant is that all PDDs have integer coefficients.
* But such a multiplication would create nodes with non-integral coefficients.
*/
pdd pdd_manager::div(pdd const& a, rational const& c) {
pdd res(zero_pdd, this);
VERIFY(try_div(a, c, res));
return res;
}
bool pdd_manager::try_div(pdd const& a, rational const& c, pdd& out_result) {
if (m_semantics == free_e) {
// Don't cache separately for the free semantics;
// use 'mul' so we can share results for a/c and a*(1/c).
out_result = mul(inv(c), a);
return true;
}
SASSERT(c.is_int());
bool first = true;
SASSERT(well_formed());
scoped_push _sp(*this);
while (true) {
try {
PDD res = div_rec(a.root, c, null_pdd);
if (res != null_pdd)
out_result = pdd(res, this);
SASSERT(well_formed());
return res != null_pdd;
}
catch (const mem_out &) {
try_gc();
if (!first) throw;
first = false;
}
}
}
/// Returns null_pdd if one of the coefficients is not divisible by c.
pdd_manager::PDD pdd_manager::div_rec(PDD a, rational const& c, PDD c_pdd) {
SASSERT(m_semantics != free_e);
SASSERT(c.is_int());
if (is_zero(a))
return zero_pdd;
if (is_val(a)) {
rational r = val(a) / c;
if (r.is_int())
return imk_val(r);
else
return null_pdd;
}
if (c_pdd == null_pdd)
c_pdd = imk_val(c);
op_entry* e1 = pop_entry(a, c_pdd, pdd_div_const_op);
op_entry const* e2 = m_op_cache.insert_if_not_there(e1);
if (check_result(e1, e2, a, c_pdd, pdd_div_const_op))
return e2->m_result;
push(div_rec(lo(a), c, c_pdd));
push(div_rec(hi(a), c, c_pdd));
PDD l = read(2);
PDD h = read(1);
PDD res = null_pdd;
if (l != null_pdd && h != null_pdd)
res = make_node(level(a), l, h);
pop(2);
e1->m_result = res;
return res;
}
pdd pdd_manager::pow(pdd const &p, unsigned j) {
return pdd(pow(p.root, j), this);
}
pdd_manager::PDD pdd_manager::pow(PDD p, unsigned j) {
if (j == 0)
return one_pdd;
else if (j == 1)
return p;
else if (is_zero(p))
return zero_pdd;
else if (is_one(p))
return one_pdd;
else if (is_val(p))
return imk_val(power(val(p), j));
else
return pow_rec(p, j);
}
pdd_manager::PDD pdd_manager::pow_rec(PDD p, unsigned j) {
SASSERT(j > 0);
if (j == 1)
return p;
// j even: pow(p,2*j') = pow(p*p,j')
// j odd: pow(p,2*j'+1) = p*pow(p*p,j')
PDD q = pow_rec(apply(p, p, pdd_mul_op), j / 2);
if (j & 1) {
q = apply(q, p, pdd_mul_op);
}
return q;
}
//
// produce polynomial where a is reduced by b.
// all monomials in a that are divisible by lm(b)
@ -691,27 +838,37 @@ namespace dd {
* factor p into lc*v^degree + rest
* such that degree(rest, v) < degree
* Initial implementation is very naive
* - memoize intermediary results
*/
void pdd_manager::factor(pdd const& p, unsigned v, unsigned degree, pdd& lc, pdd& rest) {
unsigned level_v = m_var2level[v];
if (degree == 0) {
lc = p;
rest = zero();
}
else if (level(p.root) < level_v) {
lc = zero();
rest = p;
return;
}
else if (level(p.root) > level_v) {
if (level(p.root) < level_v) {
lc = zero();
rest = p;
return;
}
// Memoize nontrivial cases
auto* et = m_factor_cache.insert_if_not_there2({p.root, v, degree});
factor_entry* e = &et->get_data();
if (e->is_valid()) {
lc = pdd(e->m_lc, this);
rest = pdd(e->m_rest, this);
return;
}
if (level(p.root) > level_v) {
pdd lc1 = zero(), rest1 = zero();
pdd vv = mk_var(p.var());
factor(p.hi(), v, degree, lc, rest);
factor(p.lo(), v, degree, lc1, rest1);
lc += lc1;
rest += rest1;
lc *= vv;
rest *= vv;
lc += lc1;
rest += rest1;
}
else {
unsigned d = 0;
@ -733,8 +890,228 @@ namespace dd {
rest = p;
}
}
et = m_factor_cache.insert_if_not_there2({p.root, v, degree});
e = &et->get_data();
e->m_lc = lc.root;
e->m_rest = rest.root;
}
bool pdd_manager::factor(pdd const& p, unsigned v, unsigned degree, pdd& lc) {
pdd rest = lc;
factor(p, v, degree, lc, rest);
return rest.is_zero();
}
/**
* Apply function f to all coefficients of the polynomial.
* The function should be of type
* rational const& -> rational
* rational const& -> unsigned
* and should always return integers.
*
* NOTE: the operation is not cached.
*/
template <class Fn>
pdd pdd_manager::map_coefficients(pdd const& p, Fn f) {
if (p.is_val()) {
return mk_val(rational(f(p.val())));
} else {
pdd x = mk_var(p.var());
pdd lo = map_coefficients(p.lo(), f);
pdd hi = map_coefficients(p.hi(), f);
return x*hi + lo;
}
}
/**
* Perform S-polynomial reduction on p by q,
* treating monomial with v as leading.
*
* p = a v^l + b = a' 2^j v^l + b
* q = c v^m + d = c' 2^j v^m + d
* such that
* deg(v, p) = l, i.e., v does not divide a and there is no v^l in b
* deg(v, q) = m, i.e., v does not divide c and there is no v^m in d
* l >= m
* j maximal, i.e., not both of a', c' are divisible by 2
*
* Then we reduce p by q:
*
* r = c' p - a' v^(l-m) q
* = b c' - a' d v^(l-m)
*/
bool pdd_manager::resolve(unsigned v, pdd const& p, pdd const& q, pdd& r) {
unsigned const l = p.degree(v);
unsigned const m = q.degree(v);
// no reduction
if (l < m || m == 0)
return false;
pdd a = zero();
pdd b = zero();
pdd c = zero();
pdd d = zero();
p.factor(v, l, a, b);
q.factor(v, m, c, d);
unsigned const j = std::min(max_pow2_divisor(a), max_pow2_divisor(c));
SASSERT(j != UINT_MAX); // should only be possible when both l and m are 0
rational const pow2j = rational::power_of_two(j);
pdd const aa = div(a, pow2j);
pdd const cc = div(c, pow2j);
pdd vv = pow(mk_var(v), l - m);
r = b * cc - aa * d * vv;
return true;
}
/**
* Reduce polynomial a with respect to b by eliminating terms using v
*
* a := a1*v^l + a2
* b := b1*v^m + b2
* l >= m
* q, r := quot_rem(a1, b1)
* that is:
* q * b1 + r = a1
* r = 0
* result := reduce(v, q*b2*v^{l-m}, b) + reduce(v, a2, b)
*/
pdd pdd_manager::reduce(unsigned v, pdd const& a, pdd const& b) {
unsigned const m = b.degree(v);
// no reduction
if (m == 0)
return a;
pdd b1 = zero();
pdd b2 = zero();
b.factor(v, m, b1, b2);
// TODO - generalize this case to when leading coefficient is not a value
if (m_semantics == mod2N_e && b1.is_val() && b1.val().is_odd() && !b1.is_one()) {
rational b_inv;
VERIFY(b1.val().mult_inverse(m_power_of_2, b_inv));
b1 = 1;
b2 *= b_inv;
}
return reduce(v, a, m, b1, b2);
}
pdd pdd_manager::reduce(unsigned v, pdd const& a, unsigned m, pdd const& b1, pdd const& b2) {
SASSERT(m > 0);
unsigned const l = a.degree(v);
if (l < m)
return a;
pdd a1 = zero();
pdd a2 = zero();
pdd q = zero();
pdd r = zero();
a.factor(v, l, a1, a2);
quot_rem(a1, b1, q, r);
if (r.is_zero()) {
SASSERT(q * b1 == a1);
a1 = -q * b2;
if (l > m)
a1 = reduce(v, a1 * pow(mk_var(v), l - m), m, b1, b2);
}
else
a1 = a1 * pow(mk_var(v), l);
a2 = reduce(v, a2, m, b1, b2);
return a1 + a2;
}
/**
* quotient/remainder of 'a' divided by 'b'
* a := x*hi + lo
* x > level(b):
* hi = q1*b + r1
* lo = q2*b + r2
* x*hi + lo = (x*q1 + q2)*b + (x*r1 + r2)
* q := x*q1 + q2
* r := x*r1 + r2
* Some special cases.
* General multi-variable polynomial division is TBD.
*/
void pdd_manager::quot_rem(pdd const& a, pdd const& b, pdd& q, pdd& r) {
if (level(a.root) > level(b.root)) {
pdd q1(*this), q2(*this), r1(*this), r2(*this);
quot_rem(a.hi(), b, q1, r1);
quot_rem(a.lo(), b, q2, r2);
q = mk_var(a.var()) * q1 + q2;
r = mk_var(a.var()) * r1 + r2;
}
else if (level(a.root) < level(b.root)) {
q = zero();
r = a;
}
else if (a == b) {
q = one();
r = zero();
}
else if (a.is_val() && b.is_val() && divides(b.val(), a.val())) {
q = mk_val(a.val() / b.val());
r = zero();
}
else if (a.is_val() || b.is_val()) {
q = zero();
r = a;
}
else {
SASSERT(level(a.root) == level(b.root));
pdd q1(*this), q2(*this), r1(*this), r2(*this);
quot_rem(a.hi(), b.hi(), q1, r1);
quot_rem(a.lo(), b.lo(), q2, r2);
if (q1 == q2 && r1.is_zero() && r2.is_zero()) {
q = q1;
r = zero();
}
else {
q = zero();
r = a;
}
}
}
/**
* Returns the largest j such that 2^j divides p.
*/
unsigned pdd_manager::max_pow2_divisor(PDD p) {
init_mark();
unsigned min_j = UINT_MAX;
m_todo.push_back(p);
while (!m_todo.empty()) {
PDD r = m_todo.back();
m_todo.pop_back();
if (is_marked(r)) {
continue;
}
set_mark(r);
if (is_zero(r)) {
// skip
}
else if (is_val(r)) {
rational const& c = val(r);
if (c.is_odd()) {
m_todo.reset();
return 0;
} else {
unsigned j = c.trailing_zeros();
min_j = std::min(j, min_j);
}
}
else {
m_todo.push_back(lo(r));
m_todo.push_back(hi(r));
}
}
return min_j;
}
unsigned pdd_manager::max_pow2_divisor(pdd const& p) {
return max_pow2_divisor(p.root);
}
bool pdd_manager::is_linear(pdd const& p) {
return is_linear(p.root);
@ -764,6 +1141,32 @@ namespace dd {
}
}
/** Determine whether p contains at most one variable. */
bool pdd_manager::is_univariate(PDD p) {
unsigned const lvl = level(p);
while (!is_val(p)) {
if (!is_val(lo(p)))
return false;
if (level(p) != lvl)
return false;
p = hi(p);
}
return true;
}
/**
* Push coefficients of univariate polynomial in order of ascending degree.
* Example: a*x^2 + b*x + c ==> [ c, b, a ]
*/
void pdd_manager::get_univariate_coefficients(PDD p, vector<rational>& coeff) {
SASSERT(is_univariate(p));
while (!is_val(p)) {
coeff.push_back(val(lo(p)));
p = hi(p);
}
coeff.push_back(val(p));
}
/*
\brief determine if v occurs as a leaf variable.
*/
@ -832,9 +1235,8 @@ namespace dd {
if (m_semantics == mod2N_e && (r < 0 || r >= m_mod2N))
return imk_val(mod(r, m_mod2N));
const_info info;
if (!m_mpq_table.find(r, info)) {
if (!m_mpq_table.find(r, info))
init_value(info, r);
}
return info.m_node_index;
}
@ -1005,7 +1407,7 @@ namespace dd {
unsigned pdd_manager::degree(PDD p, unsigned v) {
init_mark();
unsigned level_v = level(v);
unsigned level_v = m_var2level[v];
unsigned max_d = 0, d = 0;
m_todo.push_back(p);
while (!m_todo.empty()) {
@ -1017,15 +1419,17 @@ namespace dd {
else if (level(r) < level_v)
m_todo.pop_back();
else if (level(r) == level_v) {
d = 1;
while (!is_val(hi(r)) && level(hi(r)) == level_v) {
d = 0;
do {
++d;
set_mark(r);
r = hi(r);
}
} while (!is_val(r) && level(r) == level_v);
max_d = std::max(d, max_d);
m_todo.pop_back();
}
else {
set_mark(r);
m_todo.push_back(lo(r));
m_todo.push_back(hi(r));
}
@ -1128,6 +1532,7 @@ namespace dd {
}
void pdd_manager::gc() {
m_gc_generation++;
init_dmark();
m_free_nodes.reset();
SASSERT(well_formed());
@ -1167,6 +1572,8 @@ namespace dd {
m_op_cache.insert(e);
}
m_factor_cache.reset();
m_node_table.reset();
// re-populate node cache
for (unsigned i = m_nodes.size(); i-- > 2; ) {
@ -1221,14 +1628,32 @@ namespace dd {
rational c = abs(m.first);
m.second.reverse();
if (!c.is_one() || m.second.empty()) {
out << c;
if (m_semantics == mod2N_e && mod(-c, m_mod2N) < c)
out << -mod(-c, m_mod2N);
else
out << c;
if (!m.second.empty()) out << "*";
}
bool f = true;
unsigned v_prev = UINT_MAX;
unsigned pow = 0;
for (unsigned v : m.second) {
if (!f) out << "*";
f = false;
out << "v" << v;
if (v == v_prev) {
pow++;
continue;
}
if (v_prev != UINT_MAX) {
out << "v" << v_prev;
if (pow > 1)
out << "^" << pow;
out << "*";
}
pow = 1;
v_prev = v;
}
if (v_prev != UINT_MAX) {
out << "v" << v_prev;
if (pow > 1)
out << "^" << pow;
}
}
if (first) out << "0";
@ -1291,6 +1716,30 @@ namespace dd {
return *this;
}
pdd& pdd::operator=(unsigned k) {
m.dec_ref(root);
root = m.mk_val(k).root;
m.inc_ref(root);
return *this;
}
pdd& pdd::operator=(rational const& k) {
m.dec_ref(root);
root = m.mk_val(k).root;
m.inc_ref(root);
return *this;
}
rational const& pdd::leading_coefficient() const {
pdd p = *this;
while (!p.is_val())
p = p.hi();
return p.val();
}
pdd pdd::shl(unsigned n) const {
return (*this) * rational::power_of_two(n);
}
/**
* \brief substitute variable v by r.

View file

@ -23,6 +23,11 @@ Abstract:
- try_spoly(a, b, c) returns true if lt(a) and lt(b) have a non-trivial overlap. c is the resolvent (S polynomial).
- reduce(v, a, b) reduces 'a' using b = 0 with respect to eliminating v.
Given b = v^l*b1 + b2, where l is the leading coefficient of v in b
Given a = v^m*a1 + b2, where m >= l is the leading coefficient of v in b.
reduce(a1, b1)*v^{m - l} + reduce(v, a2, b);
Author:
Nikolaj Bjorner (nbjorner) 2019-12-17
@ -63,7 +68,9 @@ namespace dd {
pdd_mul_op = 5,
pdd_reduce_op = 6,
pdd_subst_val_op = 7,
pdd_no_op = 8
pdd_subst_add_op = 8,
pdd_div_const_op = 9,
pdd_no_op = 10
};
struct node {
@ -140,9 +147,44 @@ namespace dd {
typedef ptr_hashtable<op_entry, hash_entry, eq_entry> op_table;
struct factor_entry {
factor_entry(PDD p, unsigned v, unsigned degree):
m_p(p),
m_v(v),
m_degree(degree),
m_lc(UINT_MAX),
m_rest(UINT_MAX)
{}
factor_entry(): m_p(0), m_v(0), m_degree(0), m_lc(UINT_MAX), m_rest(UINT_MAX) {}
PDD m_p; // input
unsigned m_v; // input
unsigned m_degree; // input
PDD m_lc; // output
PDD m_rest; // output
bool is_valid() { return m_lc != UINT_MAX; }
unsigned hash() const { return mk_mix(m_p, m_v, m_degree); }
};
struct hash_factor_entry {
unsigned operator()(factor_entry const& e) const { return e.hash(); }
};
struct eq_factor_entry {
bool operator()(factor_entry const& a, factor_entry const& b) const {
return a.m_p == b.m_p && a.m_v == b.m_v && a.m_degree == b.m_degree;
}
};
typedef hashtable<factor_entry, hash_factor_entry, eq_factor_entry> factor_table;
svector<node> m_nodes;
vector<rational> m_values;
op_table m_op_cache;
factor_table m_factor_cache;
node_table m_node_table;
mpq_table m_mpq_table;
svector<PDD> m_pdd_stack;
@ -164,7 +206,9 @@ namespace dd {
unsigned_vector m_free_values;
rational m_freeze_value;
rational m_mod2N;
unsigned m_power_of_2 { 0 };
unsigned m_power_of_2 = 0;
rational m_max_value;
unsigned m_gc_generation = 0; ///< will be incremented on each GC
void reset_op_cache();
void init_nodes(unsigned_vector const& l2v);
@ -177,6 +221,9 @@ namespace dd {
PDD apply(PDD arg1, PDD arg2, pdd_op op);
PDD apply_rec(PDD arg1, PDD arg2, pdd_op op);
PDD minus_rec(PDD p);
PDD div_rec(PDD p, rational const& c, PDD c_pdd);
PDD pow(PDD p, unsigned j);
PDD pow_rec(PDD p, unsigned j);
PDD reduce_on_match(PDD a, PDD b);
bool lm_occurs(PDD p, PDD q) const;
@ -206,7 +253,8 @@ namespace dd {
inline bool is_one(PDD p) const { return p == one_pdd; }
inline bool is_val(PDD p) const { return m_nodes[p].is_val(); }
inline bool is_internal(PDD p) const { return m_nodes[p].is_internal(); }
bool is_non_zero(PDD p);
inline bool is_var(PDD p) const { return !is_val(p) && is_zero(lo(p)) && is_one(hi(p)); }
bool is_never_zero(PDD p);
inline unsigned level(PDD p) const { return m_nodes[p].m_level; }
inline unsigned var(PDD p) const { return m_level2var[level(p)]; }
inline PDD lo(PDD p) const { return m_nodes[p].m_lo; }
@ -226,8 +274,14 @@ namespace dd {
unsigned degree(pdd const& p) const;
unsigned degree(PDD p) const;
unsigned degree(PDD p, unsigned v);
unsigned max_pow2_divisor(PDD p);
unsigned max_pow2_divisor(pdd const& p);
template <class Fn> pdd map_coefficients(pdd const& p, Fn f);
void factor(pdd const& p, unsigned v, unsigned degree, pdd& lc, pdd& rest);
bool factor(pdd const& p, unsigned v, unsigned degree, pdd& lc);
pdd reduce(unsigned v, pdd const& a, unsigned m, pdd const& b1, pdd const& b2);
bool var_is_leaf(PDD p, unsigned v);
@ -258,7 +312,7 @@ namespace dd {
struct mem_out {};
pdd_manager(unsigned nodes, semantics s = free_e, unsigned power_of_2 = 0);
pdd_manager(unsigned num_vars, semantics s = free_e, unsigned power_of_2 = 0);
~pdd_manager();
semantics get_semantics() const { return m_semantics; }
@ -278,13 +332,21 @@ namespace dd {
pdd sub(pdd const& a, pdd const& b);
pdd mul(pdd const& a, pdd const& b);
pdd mul(rational const& c, pdd const& b);
pdd div(pdd const& a, rational const& c);
bool try_div(pdd const& a, rational const& c, pdd& out_result);
pdd mk_or(pdd const& p, pdd const& q);
pdd mk_xor(pdd const& p, pdd const& q);
pdd mk_xor(pdd const& p, unsigned q);
pdd mk_not(pdd const& p);
pdd reduce(pdd const& a, pdd const& b);
pdd subst_val(pdd const& a, vector<std::pair<unsigned, rational>> const& s);
pdd subst_val0(pdd const& a, vector<std::pair<unsigned, rational>> const& s);
pdd subst_val(pdd const& a, unsigned v, rational const& val);
pdd subst_val(pdd const& a, pdd const& s);
pdd subst_add(pdd const& s, unsigned v, rational const& val);
bool resolve(unsigned v, pdd const& p, pdd const& q, pdd& r);
pdd reduce(unsigned v, pdd const& a, pdd const& b);
void quot_rem(pdd const& a, pdd const& b, pdd& q, pdd& r);
pdd pow(pdd const& p, unsigned j);
bool is_linear(PDD p) { return degree(p) == 1; }
bool is_linear(pdd const& p);
@ -294,6 +356,9 @@ namespace dd {
bool is_monomial(PDD p);
bool is_univariate(PDD p);
void get_univariate_coefficients(PDD p, vector<rational>& coeff);
// create an spoly r if leading monomials of a and b overlap
bool try_spoly(pdd const& a, pdd const& b, pdd& r);
@ -308,6 +373,8 @@ namespace dd {
unsigned num_vars() const { return m_var2pdd.size(); }
unsigned power_of_2() const { return m_power_of_2; }
rational const& max_value() const { return m_max_value; }
rational const& two_to_N() const { return m_mod2N; }
unsigned_vector const& free_vars(pdd const& p);
@ -330,21 +397,30 @@ namespace dd {
pdd(pdd const& other): root(other.root), m(other.m) { m.inc_ref(root); }
pdd(pdd && other) noexcept : root(0), m(other.m) { std::swap(root, other.root); }
pdd& operator=(pdd const& other);
pdd& operator=(unsigned k);
pdd& operator=(rational const& k);
~pdd() { m.dec_ref(root); }
pdd lo() const { return pdd(m.lo(root), m); }
pdd hi() const { return pdd(m.hi(root), m); }
unsigned index() const { return root; }
unsigned var() const { return m.var(root); }
rational const& val() const { SASSERT(is_val()); return m.val(root); }
rational const& leading_coefficient() const;
bool is_val() const { return m.is_val(root); }
bool is_one() const { return m.is_one(root); }
bool is_zero() const { return m.is_zero(root); }
bool is_linear() const { return m.is_linear(root); }
bool is_var() const { return m.is_var(root); }
/** Polynomial is of the form a * x + b for numerals a, b. */
bool is_unilinear() const { return !is_val() && lo().is_val() && hi().is_val(); }
bool is_unary() const { return !is_val() && lo().is_zero() && hi().is_val(); }
bool is_offset() const { return !is_val() && lo().is_val() && hi().is_one(); }
bool is_binary() const { return m.is_binary(root); }
bool is_monomial() const { return m.is_monomial(root); }
bool is_non_zero() const { return m.is_non_zero(root); }
bool is_univariate() const { return m.is_univariate(root); }
void get_univariate_coefficients(vector<rational>& coeff) const { m.get_univariate_coefficients(root, coeff); }
vector<rational> get_univariate_coefficients() const { vector<rational> coeff; m.get_univariate_coefficients(root, coeff); return coeff; }
bool is_never_zero() const { return m.is_never_zero(root); }
bool var_is_leaf(unsigned v) const { return m.var_is_leaf(root, v); }
pdd operator-() const { return m.minus(*this); }
@ -359,20 +435,28 @@ namespace dd {
pdd operator*(rational const& other) const { return m.mul(other, *this); }
pdd operator+(rational const& other) const { return m.add(other, *this); }
pdd operator~() const { return m.mk_not(*this); }
pdd shl(unsigned n) const;
pdd rev_sub(rational const& r) const { return m.sub(m.mk_val(r), *this); }
pdd div(rational const& other) const { return m.div(*this, other); }
bool try_div(rational const& other, pdd& out_result) const { return m.try_div(*this, other, out_result); }
pdd pow(unsigned j) const { return m.pow(*this, j); }
pdd reduce(pdd const& other) const { return m.reduce(*this, other); }
bool different_leading_term(pdd const& other) const { return m.different_leading_term(*this, other); }
void factor(unsigned v, unsigned degree, pdd& lc, pdd& rest) { m.factor(*this, v, degree, lc, rest); }
void factor(unsigned v, unsigned degree, pdd& lc, pdd& rest) const { m.factor(*this, v, degree, lc, rest); }
bool factor(unsigned v, unsigned degree, pdd& lc) const { return m.factor(*this, v, degree, lc); }
bool resolve(unsigned v, pdd const& other, pdd& result) { return m.resolve(v, *this, other, result); }
pdd reduce(unsigned v, pdd const& other) const { return m.reduce(v, *this, other); }
/**
* \brief factor out variables
*/
std::pair<unsigned_vector, pdd> var_factors() const;
pdd subst_val(vector<std::pair<unsigned, rational>> const& s) const { return m.subst_val(*this, s); }
pdd subst_val0(vector<std::pair<unsigned, rational>> const& s) const { return m.subst_val0(*this, s); }
pdd subst_val(pdd const& s) const { return m.subst_val(*this, s); }
pdd subst_val(unsigned v, rational const& val) const { return m.subst_val(*this, v, val); }
pdd subst_add(unsigned var, rational const& val) { return m.subst_add(*this, var, val); }
/**
* \brief substitute variable v by r.
*/
@ -381,6 +465,7 @@ namespace dd {
std::ostream& display(std::ostream& out) const { return m.display(out, *this); }
bool operator==(pdd const& other) const { return root == other.root; }
bool operator!=(pdd const& other) const { return root != other.root; }
unsigned hash() const { return root; }
unsigned power_of_2() const { return m.power_of_2(); }
@ -388,11 +473,15 @@ namespace dd {
double tree_size() const { return m.tree_size(*this); }
unsigned degree() const { return m.degree(*this); }
unsigned degree(unsigned v) const { return m.degree(root, v); }
unsigned max_pow2_divisor() const { return m.max_pow2_divisor(root); }
unsigned_vector const& free_vars() const { return m.free_vars(*this); }
void swap(pdd& other) { std::swap(root, other.root); }
pdd_iterator begin() const;
pdd_iterator end() const;
pdd_manager& manager() const { return m; }
};
inline pdd operator*(rational const& r, pdd const& b) { return b * r; }
@ -403,23 +492,25 @@ namespace dd {
inline pdd operator+(int x, pdd const& b) { return b + rational(x); }
inline pdd operator+(pdd const& b, int x) { return b + rational(x); }
inline pdd operator^(unsigned x, pdd const& b) { return b + x; }
inline pdd operator^(bool x, pdd const& b) { return b + x; }
inline pdd operator^(unsigned x, pdd const& b) { return b ^ x; }
inline pdd operator^(bool x, pdd const& b) { return b ^ x; }
inline pdd operator-(rational const& r, pdd const& b) { return b.rev_sub(r); }
inline pdd operator-(int x, pdd const& b) { return rational(x) - b; }
inline pdd operator-(pdd const& b, int x) { return b + (-rational(x)); }
inline pdd operator-(pdd const& b, rational const& r) { return b + (-r); }
inline pdd& operator&=(pdd & p, pdd const& q) { p = p & q; return p; }
inline pdd& operator^=(pdd & p, pdd const& q) { p = p ^ q; return p; }
inline pdd& operator*=(pdd & p, pdd const& q) { p = p * q; return p; }
inline pdd& operator|=(pdd & p, pdd const& q) { p = p | q; return p; }
inline pdd& operator*=(pdd & p, pdd const& q) { p = p * q; return p; }
inline pdd& operator-=(pdd & p, pdd const& q) { p = p - q; return p; }
inline pdd& operator+=(pdd & p, pdd const& q) { p = p + q; return p; }
inline pdd& operator+=(pdd & p, rational const& v) { p = p + v; return p; }
inline pdd& operator-=(pdd & p, rational const& v) { p = p - v; return p; }
inline pdd& operator*=(pdd & p, rational const& v) { p = p * v; return p; }
inline pdd& operator*=(pdd & p, rational const& q) { p = p * q; return p; }
inline pdd& operator-=(pdd & p, rational const& q) { p = p - q; return p; }
inline pdd& operator+=(pdd & p, rational const& q) { p = p + q; return p; }
inline void swap(pdd& p, pdd& q) { p.swap(q); }
std::ostream& operator<<(std::ostream& out, pdd const& b);

View file

@ -4,7 +4,7 @@
namespace dd {
class test {
public :
public:
static void hello_world() {
pdd_manager m(3);
@ -310,17 +310,288 @@ public :
sub1.push_back(std::make_pair(va, rational(1)));
sub2.push_back(std::make_pair(va, rational(2)));
sub3.push_back(std::make_pair(va, rational(3)));
std::cout << "sub 0 " << p.subst_val(sub0) << "\n";
std::cout << "sub 1 " << p.subst_val(sub1) << "\n";
std::cout << "sub 2 " << p.subst_val(sub2) << "\n";
std::cout << "sub 3 " << p.subst_val(sub3) << "\n";
std::cout << "sub 0 " << p.subst_val0(sub0) << "\n";
std::cout << "sub 1 " << p.subst_val0(sub1) << "\n";
std::cout << "sub 2 " << p.subst_val0(sub2) << "\n";
std::cout << "sub 3 " << p.subst_val0(sub3) << "\n";
std::cout << "expect 1 " << (2*a + 1).is_non_zero() << "\n";
std::cout << "expect 1 " << (2*a*b + 2*b + 1).is_non_zero() << "\n";
std::cout << "expect 0 " << (2*a + 2).is_non_zero() << "\n";
SASSERT((2*a + 1).is_non_zero());
SASSERT((2*a + 2*b + 1).is_non_zero());
SASSERT(!(2*a*b + 3*b + 2).is_non_zero());
std::cout << "expect 1 " << (2*a + 1).is_never_zero() << "\n";
std::cout << "expect 1 " << (2*a*b + 2*b + 1).is_never_zero() << "\n";
std::cout << "expect 0 " << (2*a + 2).is_never_zero() << "\n";
VERIFY((2*a + 1).is_never_zero());
VERIFY((2*a + 2*b + 1).is_never_zero());
VERIFY(!(2*a*b + 3*b + 2).is_never_zero());
}
static void degree_of_variables() {
std::cout << "degree of variables\n";
pdd_manager m(4, pdd_manager::mod2N_e, 3);
unsigned va = 0;
unsigned vb = 1;
unsigned vc = 2;
pdd a = m.mk_var(va);
pdd b = m.mk_var(vb);
pdd c = m.mk_var(vc);
VERIFY(a.var() == va);
VERIFY(b.var() == vb);
VERIFY(a.degree(va) == 1);
VERIFY(a.degree(vb) == 0);
VERIFY(a.degree(vc) == 0);
VERIFY(c.degree(vc) == 1);
VERIFY(c.degree(vb) == 0);
VERIFY(c.degree(va) == 0);
{
pdd p = a * a * a;
VERIFY(p.degree(va) == 3);
VERIFY(p.degree(vb) == 0);
}
{
pdd p = b * a;
VERIFY(p.degree(va) == 1);
VERIFY(p.degree(vb) == 1);
VERIFY(p.degree(vc) == 0);
}
{
pdd p = (a*a*b + b*a*b + b + a*c)*a + b*b*c;
VERIFY(p.degree(va) == 3);
VERIFY(p.degree(vb) == 2);
VERIFY(p.degree(vc) == 1);
}
{
// check that skipping marked nodes works (1)
pdd p = b*a + c*a*a*a;
VERIFY(p.degree(va) == 3);
}
{
// check that skipping marked nodes works (2)
pdd p = (b+c)*(a*a*a);
VERIFY(p.degree(va) == 3);
}
{
// check that skipping marked nodes works (3)
pdd p = a*a*a*b*b*b*c + a*a*a*b*b*b;
VERIFY(p.degree(va) == 3);
}
}
static void factor() {
std::cout << "factor\n";
pdd_manager m(4, pdd_manager::mod2N_e, 3);
unsigned const va = 0;
unsigned const vb = 1;
unsigned const vc = 2;
unsigned const vd = 3;
pdd const a = m.mk_var(va);
pdd const b = m.mk_var(vb);
pdd const c = m.mk_var(vc);
pdd const d = m.mk_var(vd);
auto test_one = [&m](pdd const& p, unsigned v, unsigned d) {
pdd lc = m.zero();
pdd rest = m.zero();
std::cout << "Factoring p = " << p << " by v" << v << "^" << d << "\n";
p.factor(v, d, lc, rest);
std::cout << " lc = " << lc << "\n";
std::cout << " rest = " << rest << "\n";
pdd x = m.mk_var(v);
pdd x_pow_d = m.one();
for (unsigned i = 0; i < d; ++i) {
x_pow_d *= x;
}
VERIFY( p == lc * x_pow_d + rest );
VERIFY( d == 0 || rest.degree(v) < d );
VERIFY( d != 0 || lc.is_zero() );
};
auto test_multiple = [=](pdd const& p) {
for (auto v : {va, vb, vc, vd}) {
for (unsigned d = 0; d <= 5; ++d) {
test_one(p, v, d);
}
}
};
test_multiple( b );
test_multiple( b*b*b );
test_multiple( b + c );
test_multiple( a*a*a*a*a + a*a*a*b + a*a*b*b + c );
test_multiple( c*c*c*c*c + b*b*b*c + 3*b*c*c + a );
test_multiple( (a + b) * (b + c) * (c + d) * (d + a) );
}
static void max_pow2_divisor() {
std::cout << "max_pow2_divisor\n";
pdd_manager m(4, pdd_manager::mod2N_e, 256);
unsigned const va = 0;
unsigned const vb = 1;
pdd const a = m.mk_var(va);
pdd const b = m.mk_var(vb);
VERIFY(m.zero().max_pow2_divisor() == UINT_MAX);
VERIFY(m.one().max_pow2_divisor() == 0);
pdd p = (1 << 20)*a*b + 1024*b*b*b;
std::cout << p << " divided by 2^" << p.max_pow2_divisor() << "\n";
VERIFY(p.max_pow2_divisor() == 10);
VERIFY(p.div(rational::power_of_two(10)) == 1024*a*b + b*b*b);
VERIFY((p + p).max_pow2_divisor() == 11);
VERIFY((p * p).max_pow2_divisor() == 20);
VERIFY((p + 2*b).max_pow2_divisor() == 1);
VERIFY((p + b*b*b).max_pow2_divisor() == 0);
}
static void try_div() {
std::cout << "try_div\n";
pdd_manager m(4, pdd_manager::mod2N_e, 256);
pdd const a = m.mk_var(0);
pdd const b = m.mk_var(1);
pdd const p = 5*a + 15*a*b;
VERIFY_EQ(p.div(rational(5)), a + 3*a*b);
pdd res = a;
VERIFY(!p.try_div(rational(3), res));
}
static void binary_resolve() {
std::cout << "binary resolve\n";
pdd_manager m(4, pdd_manager::mod2N_e, 4);
unsigned const va = 0;
unsigned const vb = 1;
unsigned const vc = 2;
pdd const a = m.mk_var(va);
pdd const b = m.mk_var(vb);
pdd const c = m.mk_var(vc);
pdd r = m.zero();
pdd p = a*a*b - a*a;
pdd q = a*b*b - b*b;
VERIFY(m.resolve(va, p, q, r));
VERIFY(r == a*b*b*b - a*b*b);
VERIFY(!m.resolve(va, q, p, r));
VERIFY(!m.resolve(vb, p, q, r));
VERIFY(m.resolve(vb, q, p, r));
VERIFY(r == a*a*a*b - a*a*b);
VERIFY(!m.resolve(vc, p, q, r));
p = 2*a*a*b + 13*a*a;
q = 6*a*b*b*b + 14*b*b*b;
VERIFY(m.resolve(va, p, q, r));
VERIFY(r == (2*b+13)*2*b*b*b*a);
VERIFY(!m.resolve(va, q, p, r));
VERIFY(!m.resolve(vb, p, q, r));
VERIFY(m.resolve(vb, q, p, r));
VERIFY(r == 9*a*a*a*b*b + 5*a*a*b*b);
p = a*a*b - a*a + 4*a*c + 2;
q = 3*b*b - b*b*b + 8*b*c;
VERIFY(!m.resolve(va, p, q, r));
VERIFY(!m.resolve(va, q, p, r));
VERIFY(!m.resolve(vb, p, q, r));
VERIFY(m.resolve(vb, q, p, r));
VERIFY(r == 2*a*a*b*b + 8*a*a*b*c + 4*a*b*b*c + 2*b*b);
VERIFY(m.resolve(vc, p, q, r));
VERIFY(r == 2*a*a*b*b - 2*a*a*b - 3*a*b*b + a*b*b*b + 4*b);
VERIFY(m.resolve(vc, q, p, r));
VERIFY(r == -(2*a*a*b*b - 2*a*a*b - 3*a*b*b + a*b*b*b + 4*b));
}
static void pow() {
std::cout << "pow\n";
pdd_manager m(4, pdd_manager::mod2N_e, 5);
unsigned const va = 0;
unsigned const vb = 1;
pdd const a = m.mk_var(va);
pdd const b = m.mk_var(vb);
VERIFY(a.pow(0) == m.one());
VERIFY(a.pow(1) == a);
VERIFY(a.pow(2) == a*a);
VERIFY(a.pow(7) == a*a*a*a*a*a*a);
VERIFY((3*a*b).pow(3) == 27*a*a*a*b*b*b);
}
static void subst_val() {
std::cout << "subst_val\n";
pdd_manager m(4, pdd_manager::mod2N_e, 2);
unsigned const va = 0;
unsigned const vb = 1;
unsigned const vc = 2;
unsigned const vd = 3;
pdd const a = m.mk_var(va);
pdd const b = m.mk_var(vb);
pdd const c = m.mk_var(vc);
pdd const d = m.mk_var(vd);
{
pdd const p = 2*a + b + 1;
VERIFY(p.subst_val(va, rational(0)) == b + 1);
}
{
pdd const p = a + 2*b;
VERIFY(p.subst_val(va, rational(0)) == 2*b);
VERIFY(p.subst_val(va, rational(2)) == 2*b + 2);
VERIFY(p.subst_val(vb, rational(0)) == a);
VERIFY(p.subst_val(vb, rational(1)) == a + 2);
VERIFY(p.subst_val(vb, rational(2)) == a);
VERIFY(p.subst_val(vb, rational(3)) == a + 2);
VERIFY(p.subst_val(va, rational(0)).subst_val(vb, rational(3)) == 2*m.one());
}
{
pdd const p = a + b + c + d;
vector<std::pair<unsigned, rational>> sub;
sub.push_back({vb, rational(2)});
sub.push_back({vc, rational(3)});
VERIFY(p.subst_val0(sub) == a + d + 1);
}
{
pdd const p = (a + b) * (b + c) * (c + d);
vector<std::pair<unsigned, rational>> sub;
sub.push_back({vb, rational(2)});
sub.push_back({vc, rational(3)});
VERIFY(p.subst_val0(sub) == (a + 2) * (d + 3));
sub.push_back({va, rational(3)});
sub.push_back({vd, rational(2)});
VERIFY(p.subst_val0(sub) == m.one());
}
}
static void univariate() {
std::cout << "univariate\n";
pdd_manager m(4, pdd_manager::mod2N_e, 4);
unsigned const va = 0;
unsigned const vb = 1;
pdd const a = m.mk_var(va);
pdd const b = m.mk_var(vb);
pdd p = a*a*b - a*a;
VERIFY(!p.is_univariate());
pdd q = 3*a*a*a + 1*a + 2;
VERIFY(q.is_univariate());
vector<rational> coeff;
q.get_univariate_coefficients(coeff);
VERIFY_EQ(coeff.size(), 4);
VERIFY_EQ(coeff[0], 2);
VERIFY_EQ(coeff[1], 1);
VERIFY_EQ(coeff[2], 0);
VERIFY_EQ(coeff[3], 3);
}
static void factors() {
@ -393,5 +664,13 @@ void tst_pdd() {
dd::test::order();
dd::test::order_lm();
dd::test::mod4_operations();
dd::test::degree_of_variables();
dd::test::factor();
dd::test::max_pow2_divisor();
dd::test::try_div();
dd::test::binary_resolve();
dd::test::pow();
dd::test::subst_val();
dd::test::univariate();
dd::test::factors();
}