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Remove duplicate solutions in the higher order matching module. Simplify solutions when higher-order matching is used, and we don't have a residue.

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2013-09-19 18:59:28 -07:00
parent ffef055e34
commit 80a1b96925
3 changed files with 92 additions and 12 deletions
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1
src/kernel/expr_eq.h
View file

@ -29,6 +29,7 @@ class expr_eq_fn {
bool apply(expr const & a0, expr const & b0) {
if (is_eqp(a0, b0)) return true;
if (!a0 || !b0) return false;
if (UseHash && a0.hash() != b0.hash()) return false;
expr const & a = m_norm(a0);
expr const & b = m_norm(b0);

84
src/library/ho_unifier.cpp
View file

@ -23,6 +23,10 @@ Author: Leonardo de Moura
#define LEAN_LIBRARY_HO_UNIFIER_MAX_SOLUTIONS std::numeric_limits<unsigned>::max()
#endif
#ifndef LEAN_LIBRARY_HO_UNIFIER_REMOVE_DUPLICATES
#define LEAN_LIBRARY_HO_UNIFIER_REMOVE_DUPLICATES true
#endif
#ifndef LEAN_LIBRARY_HO_UNIFIER_USE_NORMALIZER
#define LEAN_LIBRARY_HO_UNIFIER_USE_NORMALIZER true
#endif
@ -33,11 +37,14 @@ Author: Leonardo de Moura
namespace lean {
static name g_library_ho_unifier_max_solutions {"library", "ho_unifier", "max_solutions"};
static name g_library_ho_unifier_remove_duplicates {"library", "ho_unifier", "remove_duplicates"};
static name g_library_ho_unifier_use_normalizer {"library", "ho_unifier", "use_normalizer"};
static name g_library_ho_unifier_use_beta {"library", "ho_unifier", "use_beta"};
RegisterUnsignedOption(g_library_ho_unifier_max_solutions, LEAN_LIBRARY_HO_UNIFIER_MAX_SOLUTIONS,
"maximum number of solutions for each invocation of the higher-order unifier");
RegisterBoolOption(g_library_ho_unifier_remove_duplicates, LEAN_LIBRARY_HO_UNIFIER_REMOVE_DUPLICATES,
"remove duplicate solutions in the higher-order unification module");
RegisterBoolOption(g_library_ho_unifier_use_normalizer, LEAN_LIBRARY_HO_UNIFIER_USE_NORMALIZER,
"use normalizer in the higher-order unification module");
RegisterBoolOption(g_library_ho_unifier_use_beta, LEAN_LIBRARY_HO_UNIFIER_USE_BETA,
@ -47,6 +54,10 @@ unsigned get_ho_unifier_max_solutions(options const & opts) {
return opts.get_unsigned(g_library_ho_unifier_max_solutions, LEAN_LIBRARY_HO_UNIFIER_MAX_SOLUTIONS);
}
bool get_ho_unifier_remove_duplicates(options const & opts) {
return opts.get_bool(g_library_ho_unifier_remove_duplicates, LEAN_LIBRARY_HO_UNIFIER_REMOVE_DUPLICATES);
}
bool get_ho_unifier_use_normalizer(options const & opts) {
return opts.get_bool(g_library_ho_unifier_use_normalizer, LEAN_LIBRARY_HO_UNIFIER_USE_NORMALIZER);
}
@ -74,9 +85,11 @@ class ho_unifier::imp {
state_stack m_state_stack;
unsigned m_delayed;
unsigned m_next_state_id;
bool m_ho;
volatile bool m_interrupted;
// options
unsigned m_max_solutions;
bool m_remove_duplicates;
bool m_use_normalizer;
bool m_use_beta;
@ -116,14 +129,77 @@ class ho_unifier::imp {
void init(context const & ctx, expr const & l, expr const & r, metavar_env const & menv) {
m_next_state_id = 0;
m_ho = false;
m_state_stack.clear();
m_state_stack.push_back(mk_state(menv, cqueue()));
add_constraint(ctx, l, r);
}
list<result> save_result(list<result> const & r, metavar_env const & s, residue const & rs) {
/**
\brief Return true iff \c r already contains the solution (s, rs).
\remark We only check if \c rs is empty.
\remark \c ini_s is the initial substitution set. \c s is an extension of \c ini_s
*/
bool contains_solution(list<result> const & r, metavar_env const & s, residue const & rs, metavar_env const & ini_s) {
return
empty(rs) &&
std::any_of(r.begin(), r.end(), [&](result const & prev) {
if (!empty(prev.second))
return false;
metavar_env const & prev_s = prev.first;
// Remark, prev_s and s are extensions of ini_s
for (unsigned i = 0; i < ini_s.size(); i++) {
if (!ini_s.is_assigned(i) && prev_s.get_subst(i) != s.get_subst(i))
return false;
}
return true;
});
}
/**
\brief Cleanup the result (remove auxiliary metavariables created by higher-order matching)
\remark \c ini_s is the initial substitution set. \c s is an extension of \c ini_s
*/
metavar_env cleanup_subst(metavar_env const & s, metavar_env const & ini_s) {
metavar_env new_s;
for (unsigned i = 0; i < ini_s.size(); i++) {
new_s.mk_metavar(s.get_type(i), s.get_context(i));
expr subst = s.get_subst(i);
if (subst) {
if (m_use_beta && !ini_s.is_assigned(i)) {
// beta-reduce the substitution in order to simplify expressions built using
// higher-order matching
subst = beta_reduce(subst);
}
new_s.assign(i, subst);
}
}
return new_s;
}
/**
\brief Store a result (s, rs) into r.
If m_remove_duplicates is true, then we check if r does not already contains the solution (s, rs).
In the current implementation, we only perform the check when rs is empty.
\remark \c ini_s is the initial substitution set. \c s is an extension of \c ini_s
*/
list<result> save_result(list<result> const & r, metavar_env s, residue const & rs, metavar_env const & ini_s) {
if (empty(rs) && m_ho) {
// We only do the cleanup when we don't have a residue.
// If we have a residue, we can only remove auxiliary metavariables that do not occur in rs
s = cleanup_subst(s, ini_s);
}
if (m_remove_duplicates && contains_solution(r, s, rs, ini_s)) {
return r;
} else {
return cons(result(s, rs), r);
}
}
/**
Process <tt>a == b</tt> when:
@ -297,6 +373,7 @@ class ho_unifier::imp {
bool process_meta_app(context const & ctx, expr const & a, expr const & b) {
lean_assert(is_meta_app(a));
lean_assert(!is_meta_app(b));
m_ho = true; // mark that higher-order matching was used
expr f_a = arg(a, 0);
lean_assert(is_metavar(f_a));
state top_state = m_state_stack.back();
@ -493,6 +570,7 @@ public:
m_interrupted = false;
m_delayed = 0;
m_max_solutions = get_ho_unifier_max_solutions(opts);
m_remove_duplicates = get_ho_unifier_remove_duplicates(opts);
m_use_normalizer = get_ho_unifier_use_normalizer(opts);
m_use_beta = get_ho_unifier_use_beta(opts);
}
@ -510,7 +588,7 @@ public:
unsigned cq_size = cq.size();
if (cq.empty()) {
// no constraints left to be solved
r = save_result(r, subst_of(top_state), residue());
r = save_result(r, subst_of(top_state), residue(), menv);
num_solutions++;
m_state_stack.pop_back();
} else {
@ -529,7 +607,7 @@ public:
residue rs;
for (auto c : cq)
rs = cons(c, rs);
r = save_result(r, subst_of(top_state), rs);
r = save_result(r, subst_of(top_state), rs, menv);
num_solutions++;
reset_delayed();
m_state_stack.pop_back();

1
src/util/list.h
View file

@ -47,6 +47,7 @@ public:
operator bool() const { return m_ptr != nullptr; }
friend bool is_nil(list const & l) { return l.m_ptr == nullptr; }
friend bool empty(list const & l) { return is_nil(l); }
friend T const & head(list const & l) { lean_assert(!is_nil(l)); return l.m_ptr->m_head; }
friend list const & tail(list const & l) { lean_assert(!is_nil(l)); return l.m_ptr->m_tail; }