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feat(kernel/level): add is_geq predicate, we need it for implementing the inductive datatype validation

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2014-05-17 13:19:38 -07:00
parent 4348d5e63f
commit 18a17cd48b
2 changed files with 36 additions and 2 deletions
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23
src/kernel/level.cpp
View file

@ -659,5 +659,28 @@ bool is_equivalent(level const & lhs, level const & rhs) {
check_system("level constraints");
return lhs == rhs || normalize(lhs) == normalize(rhs);
}
bool is_geq_core(level l1, level l2) {
if (l1 == l2)
return true;
if (is_max(l2))
return is_geq(l1, max_lhs(l2)) && is_geq(l1, max_rhs(l2));
if (is_imax(l2))
return is_geq(l1, imax_lhs(l2)) && is_geq(l1, imax_rhs(l2));
if (is_max(l1))
return is_geq(max_lhs(l1), l2) || is_geq(max_rhs(l1), l2);
if (is_imax(l1))
return is_geq(imax_rhs(l1), l2);
auto p1 = to_offset(l1);
auto p2 = to_offset(l2);
if (p1.first == p2.first)
return p1.second >= p2.second;
if (p1.second == p2.second && p1.second > 0)
return is_geq(p1.first, p2.first);
return false;
}
bool is_geq(level const & l1, level const & l2) {
return is_geq_core(normalize(l1), normalize(l2));
}
}
void print(lean::level const & l) { std::cout << l << std::endl; }

15
src/kernel/level.h
View file

@ -144,6 +144,17 @@ bool is_equivalent(level const & lhs, level const & rhs);
/** \brief Return the given level expression normal form */
level normalize(level const & l);
/**
\brief If the result is true, then forall assignments \c A that assigns all parameters, globals and metavariables occuring
in \c l1 and \l2, we have that the universe level l1[A] is bigger or equal to l2[A].
\remark This function assumes l1 and l2 are normalized
*/
bool is_geq_core(level l1, level l2);
bool is_geq(level const & l1, level const & l2);
typedef list<level> levels;
bool has_meta(levels const & ls);
@ -192,8 +203,8 @@ level instantiate(level const & l, level_param_names const & ps, levels const &
std::ostream & operator<<(std::ostream & out, level const & l);
/**
\brief If the result is true, then forall assignments \c A that assigns all parameters and metavariables occuring
in \c l, eval(A, l) != zero.
\brief If the result is true, then forall assignments \c A that assigns all parameters, globals and metavariables occuring
in \c l, l[A] != zero.
*/
bool is_not_zero(level const & l);