Commit graph

466 commits

Author SHA1 Message Date
Leonardo de Moura
1ccfac5873 feat(library/simplifier): conditional rewriting
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-20 21:15:46 -08:00
Leonardo de Moura
6bcd8e3ee5 fix(library/expr_lt): use expression depth instead of size to obtain a monotonic total order on terms
It is not incorrect to use size, but it can easily overflow due to sharing.
The following script demonstrates the problem:

local f = Const("f")
local a = Const("a")
function mk_shared(d)
   if d == 0 then
      return a
   else
      local c = mk_shared(d-1)
      return f(c, c)
   end
end
print(mk_shared(33):size())

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-20 17:40:49 -08:00
Leonardo de Moura
cd19d4da01 feat(library/simplifier): memoize intermediate results
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-20 17:03:44 -08:00
Leonardo de Moura
97ead50a3e feat(builtin/Nat): flip orientation of associativity axioms for + and *
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-20 15:38:00 -08:00
Leonardo de Moura
ad219d43d9 refactor(*): semantic attachment parsing and simplification
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-20 14:44:45 -08:00
Leonardo de Moura
56f5657ee7 fix(library/simplifier): ordered rewriting
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-20 13:13:16 -08:00
Leonardo de Moura
6a63ef3bc5 feat(library/expr_lt): make sure the total order on terms is monotonic
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-20 13:07:18 -08:00
Leonardo de Moura
ac9f8f340d feat(kernel/expr): add efficient get_size() function for expressions
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-20 12:28:37 -08:00
Leonardo de Moura
913d893204 feat(library/simplifier): add support for 'permutation' rewrite rules
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-20 08:29:31 -08:00
Leonardo de Moura
8e90d17a0b fix(library/hop_match): style
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 23:28:12 -08:00
Leonardo de Moura
69d7ee316f feat(library/simplifier): improve simplification by evaluation
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 23:26:34 -08:00
Leonardo de Moura
08053c1172 feat(library/hop_match): make the higher order pattern matcher slightly stronger
It now can handle (?m t) where t is not a locally bound variable, but ?m and all free variables in t are assigned.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 20:35:50 -08:00
Leonardo de Moura
d322f63113 feat(frontends/lea): add commands for creating and managing rewrite rule sets
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 12:03:59 -08:00
Leonardo de Moura
bbf6e6a256 feat(builtin/kernel): create default rule set in the kernel, and adjust unit tests
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 11:24:20 -08:00
Leonardo de Moura
3bbadddc94 chore(library/simplifier): cleanup and add comments
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 10:54:09 -08:00
Leonardo de Moura
7492fd5a2c feat(library/simplifier): add support for simplification by evaluation
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 10:34:55 -08:00
Leonardo de Moura
11719713ec feat(library/hop_match): optionally unfold constants when performing higher order matching
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 10:32:06 -08:00
Leonardo de Moura
39c3b17eb7 feat(library/simplifier): add support for Eta-reduction in the simplifier
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 00:40:35 -08:00
Leonardo de Moura
ed009f4c88 feat(kernel/simplifier): add support for Beta-reduction in the simplifier
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-19 00:40:20 -08:00
Leonardo de Moura
32c5bc25e3 refactor(library/simplifier): cleanup rewrite_rule_set, and use it in the simplifier
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-18 20:52:33 -08:00
Leonardo de Moura
466285c577 refactor(library/simplifier): rewriter_rule_set
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-18 17:26:01 -08:00
Leonardo de Moura
feea96e84d feat(library/simplifier): add rewrite_rule_set extension for managing rewrite rules in an environment
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-18 15:43:24 -08:00
Leonardo de Moura
eae79877ae feat(library/simplifier): add rewrite_rule_set
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-18 12:50:46 -08:00
Leonardo de Moura
27ab49ae9d feat(library/simplifier): bottom-up simplifier skeleton
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-18 12:49:41 -08:00
Leonardo de Moura
40b7ed13c2 fix(tests/lean): adjust tests
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-17 19:27:32 -08:00
Leonardo de Moura
534838a36c chore(build): update automatically generated files
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-17 18:30:45 -08:00
Leonardo de Moura
d711ca4d1b feat(builtin/heq): add heq C++/Lean interface
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-17 18:30:21 -08:00
Leonardo de Moura
2434024272 fix(library/rewriter): warning in release mode
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-17 15:46:49 -08:00
Leonardo de Moura
5bee259a00 refactor(kernel): remove unnecessary universe
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-16 18:06:25 -08:00
Leonardo de Moura
a43020b31b refactor(kernel): remove heterogeneous equality
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-16 17:39:12 -08:00
Leonardo de Moura
4dc98bc73b refactor(builtin/kernel): use iff instead of = for Booleans
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-16 02:05:09 -08:00
Leonardo de Moura
d063828ff9 feat(library/kernel_bindings): expose abst_name, abst_domain and abst_body in the Lua API
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-16 00:03:16 -08:00
Leonardo de Moura
8d73fb5699 fix(library/hop_match): Lua bindings gotcha
See http://www.luafaq.org/gotchas.html#T6.4

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 23:51:26 -08:00
Leonardo de Moura
14c6218bdc chore(kernel): file name convention
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 20:06:29 -08:00
Leonardo de Moura
3238c7e2a0 feat(library/simplifier): add is_permutation_ceq predicate
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 19:53:52 -08:00
Leonardo de Moura
c73398a0b8 refactor(library/simplifier): relax rule for conditional equalities
The idea is to support conditional equations where the left-hand-side does not contain all theorem arguments, but the missing arguments can be inferred using type inference.
For example, we will be able to have the eta theorem as rewrite rule:

theorem eta {A : TypeU} {B : A → TypeU} (f : ∀ x : A, B x) : (λ x : A, f x) = f
:= funext (λ x : A, refl (f x))

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 16:06:00 -08:00
Leonardo de Moura
3daac17ea8 feat(library/simplifier): convert disequalities (a ≠ b) into equations '(a = b) = false'
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 15:30:16 -08:00
Leonardo de Moura
1176093afa refactor(library/simplifier): simplifier should only use homogeneous equalities
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 14:58:32 -08:00
Leonardo de Moura
f177c8d1ec fix(library/elaborator): missing condition
The elaborator was failing in the following higher-order constraint

   ctx |- (?M a) = (?M b)

This constraint has solution, but the missing condition was making the elaborator to reduce this problem to

   ctx |- a = b

That does not have a solution.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 14:11:36 -08:00
Leonardo de Moura
c651d3ea2d feat(library/simplifier): filter out propositions that cannot be used as conditional equations
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 12:06:27 -08:00
Leonardo de Moura
94fa987814 fix(kernel/type_checker): is_proposition method was still assuming that a Pi never has type Bool
The method is_proposition was using an optimization that became incorrect after  we identified Pi and forall.
It was assuming that any Pi expression is not a proposition.
This is not true anymore. Now, (Pi x : A, B) is a proposition if B is a proposition.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-15 11:02:52 -08:00
Leonardo de Moura
28eb980484 fix(build): C++ module dependency problem, and style
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-14 18:30:31 -08:00
Leonardo de Moura
c8e1ec87d2 feat(library/simplifier): add to_ceqs function that converts a theorem into a sequence of conditional equations
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-14 18:30:19 -08:00
Leonardo de Moura
7c2a4211a8 feat(kernel): expose imported predicate
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-14 16:41:40 -08:00
Leonardo de Moura
07059b0531 feat(library): add if_then_else Lean/C++ interface
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-14 16:10:49 -08:00
Leonardo de Moura
8217a544cc fix(library/hop_match): bugs in the higher-order matching procedure, add more tests
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-14 14:37:28 -08:00
Leonardo de Moura
4595c50f7e fix(library/hop_match): in locally bound variable management
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-13 18:06:23 -08:00
Leonardo de Moura
ccb9faf065 refactor(*): error messages
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-13 16:54:21 -08:00
Leonardo de Moura
55aa4cbfa3 feat(frontends/lean): improve error message for expressions containing unsolved metavariables
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-13 13:21:44 -08:00
Leonardo de Moura
7f818ecd92 feat(library): match procedure for higher-order patterns
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-12 17:45:24 -08:00
Leonardo de Moura
d4a7d796a5 feat(builtin): prove strong induction theorem, add < theorems
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-10 18:46:33 -08:00
Leonardo de Moura
411f14415d feat(builtin): automatically generate Lean/C++ interface for builtin theories
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-09 18:09:53 -08:00
Leonardo de Moura
2179e57db3 refactor(builtin): move if_then_else to its own module
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-09 14:08:39 -08:00
Leonardo de Moura
57640ecf19 fix(library/elaborator): array bounds
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-08 13:18:49 -08:00
Leonardo de Moura
2b2aa228e3 refactor(builtin/kernel): start with small universes
The universe constraint manager is more flexible now.
We don't need to start with a huge universe  U >= 512.
We can start small, and increase it on demand.

If module mod1 needs it, it can always add

   universe U >= 3

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-08 12:35:00 -08:00
Leonardo de Moura
cfe576f551 fix(library/elaborator): bug in the elaborator
The elaborator was not handling correctly constraints of the form

    ctx |- ?m << (Pi x : A, B)
    and
    ctx |- (Pi x : A, B) << ?m

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-08 12:10:50 -08:00
Leonardo de Moura
abf61be8f6 chore(library/tactic): remove imp_tac, it is not needed anymore
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-08 00:57:04 -08:00
Leonardo de Moura
048151487e feat(kernel): use Pi as forall/implication
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-08 00:38:39 -08:00
Leonardo de Moura
8ce6266e6b feat(library/kernel_bindings): add new predicates for kernel objects in the Lua API
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-07 17:36:54 -08:00
Leonardo de Moura
d5ddb186d9 feat(library/kernel_bindings): add load method to Lua API
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-07 14:21:24 -08:00
Leonardo de Moura
17c4cce89c fix(library/elaborator): remove_detail procedure was keeping a lot of details when typeof_mvar_justification was being used
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-07 13:24:46 -08:00
Leonardo de Moura
4424a314e0 feat(kernel): add get_universe_distance method
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-06 17:13:13 -08:00
Leonardo de Moura
5fe8c32da9 feat(kernel): use new universe contraints in the environment, allow new constraints to be added
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-06 16:46:11 -08:00
Leonardo de Moura
9eb4dc4a81 feat(kernel, library/elaborator, frontends/lean): improve how elaborator_exceptions are displayed in the Lean frontend
This commit affects different modules.
I used the following approach:
1- I store the metavariable environment at unification_failure_justifications. The idea is to capture the set of instantiated metavariables at the time of failure.
2- I added a remove_detail function. It removes propagation steps from the justification tree object. I also remove the backtracking search space associated with higher-order unificiation. I keep only the search related to case-splits due to coercions and overloads.

3- I use the metavariable environment captured at step 1 when pretty printing the justification of an elaborator_exception.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-03 17:18:23 -08:00
Leonardo de Moura
92c7145d7f feat(kernel/expr): maximize sharing before serializing
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-02 20:03:42 -08:00
Leonardo de Moura
9620b00e24 feat(kernel/metavar): is instantiate_metavars, we are also instantiating assigned metavariables that occur in the local context of unassinged ones.
This modification improves the effectiveness of the process_metavar_inst procedure in the Lean elaborator.

For example, suppose we have the constraint

   ctx |- ?M1[inst:0 ?M2] == a

If ?M1 and ?M2 are unassigned, then we have to consider the two possible solutions:

        ?M1 == a
    or
        ?M1 == #0 and ?M2 == a

On the other hand, if ?M2 is assigned to b, then we can ignore the second case.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-02 16:08:38 -08:00
Leonardo de Moura
ecc5d1bc3a refactor(kernel): move printer to library, cleanup io_state interface
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-02 13:37:50 -08:00
Leonardo de Moura
0592261847 refactor(kernel/io_state): move io_state_stream to library
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-02 13:14:21 -08:00
Leonardo de Moura
b81d3309b9 fix(kernel): remove ios hack
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-02 13:03:25 -08:00
Leonardo de Moura
9c5fa72f56 fix(library/elaborator): avoid unused variable warning in release build
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-02 12:40:41 -08:00
Leonardo de Moura
49425f1a5b feat(builtin/Nat): multiplication axioms and theorems
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-01 21:32:07 -08:00
Leonardo de Moura
b2a8f4118d feat(library/elaborator): process ho-match before normalizing
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-01 14:46:19 -08:00
Leonardo de Moura
7726ccad28 chore(builtin): rename nat, int and real modules to Nat, Int and Real.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-01 13:52:25 -08:00
Leonardo de Moura
74cae2a154 refactor(library/elaborator): remove hackish rule
After the recent fixes, the hack in process_metavar is not needed anymore.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-01 10:55:39 -08:00
Leonardo de Moura
5f29146e0b feat(library/elaborator): use is_convertible for constraints without metavariables in the elaborator
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-01 03:14:01 -08:00
Leonardo de Moura
cbd1f98365 fix(library/elaborator): bug at method process_metavar_inst, add new test that exposed the bug
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-01-01 03:02:41 -08:00
Leonardo de Moura
49698bd053 chore(library/all): remove unnecessary files
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 13:37:25 -08:00
Leonardo de Moura
08718e33dc refactor(builtin): only load the kernel and natural numbers by default
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 13:35:37 -08:00
Leonardo de Moura
a80fccea93 chore(*): cleanup builtin registration
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 12:19:00 -08:00
Leonardo de Moura
2a2f0b0d89 refactor(kernel/builtin): move helper decl macros to a separate file
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 11:51:30 -08:00
Leonardo de Moura
ecd62a1783 refactor(builtin/basic): rename basic.lean to kernel.lean
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 11:46:03 -08:00
Leonardo de Moura
4401b390fe refactor(library/arith): do not load specialfn by default
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 11:25:43 -08:00
Leonardo de Moura
72761f14e4 refactor(library/io_state): move to the kernel
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 11:20:23 -08:00
Leonardo de Moura
46a8300a2d refactor(library/arith): move real and special function declarations to .lean files
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 11:02:22 -08:00
Leonardo de Moura
c3bc6afb12 refactor(library/arith): move int and nat declarations to .lean files.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-30 10:32:14 -08:00
Leonardo de Moura
097b10e424 refactor(kernel/builtin): move builtin declarations to basic
There is a lot to be done. We should do the same for Nat, Int and Real.
We also should cleanup the file builtin.cpp and builtin.h.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-29 22:00:03 -08:00
Leonardo de Moura
37e8738a5f refactor(kernel/expr): value deserializer
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-29 20:47:14 -08:00
Leonardo de Moura
15621610e9 refactor(library/arith): replace Nat, Int, Real with simple variable decls instead of semantic attachments
This commit also fixes bugs in the Alias command.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-29 17:04:36 -08:00
Leonardo de Moura
14c3e11289 refactor(kernel/builtin): emove mk_bin_rop and mk_bin_lop to library
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-29 15:23:18 -08:00
Leonardo de Moura
df3686634d refactor(kernel/builtin): remove unnecessary predicates
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-29 12:20:29 -08:00
Leonardo de Moura
411ebbc3c1 refactor(library/basic_thms): move the proof of all basic theorems to a .Lean file
This commit also adds several new theorems that are useful for implementing the simplifier.
TODO: perhaps we should remove the declarations at basic_thms.h?

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-29 03:04:49 -08:00
Leonardo de Moura
aee1c6d3f3 feat(kernel): export/import (.olean) binary files
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-28 17:31:35 -08:00
Leonardo de Moura
755e8b735f feat(kernel/expr): serializer for kernel expressions
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-28 01:23:21 -08:00
Leonardo de Moura
f1b97b18b4 refactor(frontends/lean/parser): tactic macros, and tactic Lua bindings
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-26 15:54:53 -08:00
Leonardo de Moura
ba02132a90 feat(frontends/lean/parser): add command macros
The idea is to allow users to define their own commands using Lua.
The builtin command Find is now written in Lua.
This commit also fixes a bug in the get_formatter() Lua API.
It also adds String arguments to macros.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-26 13:00:28 -08:00
Leonardo de Moura
88235d2922 feat(library/tactic/apply_tactic): try other solutions produced by the elaborator
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-25 11:51:27 -08:00
Leonardo de Moura
8e45064f25 feat(library/tactic/apply_tactic): improved parametric apply_tactic
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-24 22:40:34 -08:00
Leonardo de Moura
75cf751959 feat(library/tactic/apply_tactic): allow apply_tac Lua binding to take expressions as argument
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-24 16:03:16 -08:00
Leonardo de Moura
6cc57cc4b5 fix(library/tactic/apply_tactic): bug in apply_tac
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-24 15:54:56 -08:00
Leonardo de Moura
cb95b14332 feat(library/tactic/apply_tactic): improve apply_tactic
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-24 14:23:06 -08:00