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feat(library/tactic/inversion_tactic): use the "simpler" compilation approach in more cases

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The approach implemented in the commit 8974d70c11ef7b9b2c5d can be
extended to indexed inductive families. See comments in the code.
This commit is contained in:
Leonardo de Moura 2015-01-01 17:37:17 -08:00
parent be9e2500ce
commit 3fb2d8bbc0
1 changed files with 37 additions and 2 deletions
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39
src/library/tactic/inversion_tactic.cpp
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@ -159,6 +159,41 @@ class inversion_tac {
m_subst.assign(n, val);
}
/** \brief We say h has independent indices IF
1- it is *not* an indexed inductive family, OR
2- it is an indexed inductive family, but all indices are distinct local constants,
and all hypotheses of g different from h and indices, do not depend on the indices.
*/
bool has_indep_indices(goal const & g, expr const & h, expr const & h_type) {
if (m_nindices == 0)
return true;
buffer<expr> args;
get_app_args(h_type, args);
lean_assert(m_nindices <= args.size());
unsigned fidx = args.size() - m_nindices;
for (unsigned i = fidx; i < args.size(); i++) {
if (!is_local(args[i]))
return false; // the indices must be local constants
for (unsigned j = fidx; j < i; j++) {
if (mlocal_name(args[j]) == mlocal_name(args[i]))
return false; // the indices must be distinct local constants
}
}
buffer<expr> hyps;
g.get_hyps(hyps);
for (expr const & h1 : hyps) {
if (mlocal_name(h1) == mlocal_name(h))
continue;
if (std::any_of(args.end() - m_nindices, args.end(), [&](expr const & arg) { return mlocal_name(arg) == mlocal_name(h1); }))
continue;
// h1 is not h nor any of the indices
// Thus, it must not depend on the indices
if (std::any_of(args.end() - m_nindices, args.end(), [&](expr const & arg) { return depends_on(h1, arg); }))
return false;
}
return true;
}
/** \brief Split hyps into two "telescopes".
- non_deps : hypotheses that do not depend on H
- deps : hypotheses that depend on H (directly or indirectly)
@ -276,7 +311,7 @@ class inversion_tac {
/** \brief Generalize h dependencies.
This tactic uses this method only for non-indexed inductive families.
This tactic uses this method only if has_indep_indices(hyps, h, h_type) returns true.
The hypotheses that depend on h are stored in deps.
*/
@ -841,7 +876,7 @@ public:
expr h_type = m_tc.whnf(mlocal_type(h)).first;
if (!is_inversion_applicable(h_type))
return optional<result>();
if (m_nindices == 0) {
if (has_indep_indices(g, h, h_type)) {
buffer<expr> deps;
goal g1 = generalize_dependecies(g, h, deps);
auto gs_imps_pair = apply_cases_on(g1, imps);