max/lean4-htt
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 2
2175 commits 1 branch 0 tags 5.3 GiB
Commit graph

42 commits

Author SHA1 Message Date
Leonardo de Moura
e9dada5e14 refactor(builtin/kernel): use standard definition for 'or' and 'and' 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-17 12:05:34 -08:00
Leonardo de Moura
c526e5ec00 feat(builtin/kernel): prove false_elim without using case 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-15 14:26:13 -08:00
Leonardo de Moura
368fcb5ff9 refactor(builtin/kernel): rename refute to by_contradiction 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-12 08:49:19 -08:00
Leonardo de Moura
a2d2e36f04 refactor(frontends/lean): remove notation for creating tuples 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-10 09:03:42 -08:00
Leonardo de Moura
c45c1748d8 refactor(builtin/kernel): reorder congr1 arguments 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-09 16:15:44 -08:00
Leonardo de Moura
f28c56b188 feat(builtin/num): add auxiliary definitions and theorems for proving the primitive recursion theorem 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-08 19:36:17 -08:00
Leonardo de Moura
1ec01f5757 refactor(builtin): merge pair.lean with kernel.lean, and add basic theorems 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-07 16:04:44 -08:00
Leonardo de Moura
ad7b13104f feat(*): add support for heterogeneous equality in the parser, elaborator and simplifier, adjusts unit test to reflect changes 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-07 15:03:16 -08:00
Leonardo de Moura
6d7ec9d7b6 refactor(kernel): add heterogeneous equality back to expr 
The main motivation is that we will be able to move equalities between universes.

For example, suppose we have
    A : (Type i)
    B : (Type i)
    H : @eq (Type j) A B
where j > i

We didn't find any trick for deducing (@eq (Type i) A B) from H.
Before this commit, heterogeneous equality as a constant with type

   heq : {A B : (Type U)} : A -> B -> Bool

So, from H, we would only be able to deduce

   (@heq (Type j) (Type j) A B)

Not being able to move the equality back to a smaller universe is
problematic in several cases. I list some instances in the end of the commit message.

With this commit, Heterogeneous equality is a special kind of expression.
It is not a constant anymore. From H, we can deduce

   H1 : A == B

That is, we are essentially "erasing" the universes when we move to heterogeneous equality.
Now, since A and B have (Type i), we can deduce (@eq (Type i) A B) from H1. The proof term is

  (to_eq (Type i) A B (to_heq (Type j) A B H))  :  (@eq (Type i) A B)

So, it remains to explain why we need this feature.

For example, suppose we want to state the Pi extensionality axiom.

axiom hpiext {A A' : (Type U)} {B : A → (Type U)} {B' : A' → (Type U)} :
      A = A' → (∀ x x', x == x' → B x == B' x') → (∀ x, B x) == (∀ x, B' x)

This axiom produces an "inflated" equality at (Type U) when we treat heterogeneous
equality as a constant. The conclusion

     (∀ x, B x) == (∀ x, B' x)

is syntax sugar for

   (@heq (Type U) (Type U) (∀ x : A, B x) (∀ x : A', B' x))

Even if A, A', B, B' live in a much smaller universe.

As I described above, it doesn't seem to be a way to move this equality back to a smaller universe.

So, if we wanted to keep the heterogeneous equality as a constant, it seems we would
have to support axiom schemas. That is, hpiext would be parametrized by the universes where
A, A', B and B'. Another possibility would be to have universe polymorphism like Agda.
None of the solutions seem attractive.

So, we decided to have heterogeneous equality as a special kind of expression.
And use the trick above to move equalities back to the right universe.

BTW, the parser is not creating the new heterogeneous equalities yet.
Moreover, kernel.lean still contains a constant name heq2 that is the heterogeneous
equality as a constant.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-07 10:28:10 -08:00
Leonardo de Moura
30570c843f feat(builtin): add optional type 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-05 17:33:06 -08:00
Leonardo de Moura
0283887ee9 refactor(builtin/kernel): move the heq axioms into kernel.lean 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-04 14:17:34 -08:00
Leonardo de Moura
9dc86e3cf5 fix(builtin/kernel): rename generalized proof_irrel axiom to hproof_irrel, and derive the restricted one 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-04 10:06:29 -08:00
Leonardo de Moura
9a677331da feat(builtin): simulate subtypes using sigma types 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-04 01:46:50 -08:00
Leonardo de Moura
c56df132b8 refactor(kernel): remove semantic attachments from the kernel 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-02 14:48:27 -08:00
Leonardo de Moura
4d533c6a25 feat(builtin/kernel): add nonempty_range theorem 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-30 22:13:34 -08:00
Leonardo de Moura
ddaf948c72 feat(builtin/kernel): add nonempty_fun theorem 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-30 19:38:51 -08:00
Leonardo de Moura
759aa61f70 refactor(builtin/kernel): define if-then-else using Hilbert's operator 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-30 19:28:42 -08:00
Leonardo de Moura
b6985bd713 feat(builtin/kernel): add another rewrite rule 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-28 15:56:26 -08:00
Leonardo de Moura
ceff335bb8 doc(doc/lean/tutorial): update tutorial 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-26 22:58:44 -08:00
Leonardo de Moura
4d25cb7f47 feat(library/tactic): add simplify_tactic based on the simplifier 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-26 18:53:18 -08:00
Leonardo de Moura
2bb33c55fe feat(builtin/kernel): add more theorems useful for simplification 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-24 18:52:50 -08:00
Leonardo de Moura
dbc100cc2e feat(library/simplifier): cast elimination in the simplifier 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-23 17:28:14 -08:00
Leonardo de Moura
33193e1ab3 feat(library/simplifier): improve contextual simplifications 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-23 12:54:29 -08:00
Leonardo de Moura
66553268d0 feat(builtin/kernel): add skolem_th, we need it to justify skolemization preprocessing step 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-22 09:41:07 -08:00
Leonardo de Moura
d9b5ebc738 refactor(builtin/kernel): cleanup Hilbert operator definition 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-22 09:18:40 -08:00
Leonardo de Moura
94a3136904 feat(builtin/kernel): add Hilbert's operator, and derive axiom of choice using it 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-22 08:21:11 -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
6db10c577b feat(builtin/kernel): add proof irrelevance axiom 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-19 12:20:09 -08:00
Leonardo de Moura
475df3d94e chore(builtin/kernel): add theorem for rewriter/simplifier 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-19 10:34:18 -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
1da4294793 refactor(builtin): more theorems, fix iff notation 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-16 09:26:50 -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
8c2f78a756 feat(builtin): minimize use of heterogenous equality in the kernel, add simpler version of congruence theorems for non-dependent types 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-15 16:34:23 -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
f8eaae7218 feat(builtin/kernel): add new useful theorems for the simplifier 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-13 18:21:22 -08:00
Leonardo de Moura
781720a26a feat(builtin/kernel): add left_comm theorem 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-11 18:08:08 -08:00
Leonardo de Moura
a1a467a65f refactor(builtin): move congruence theorems to kernel/if_then_else modules 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-11 13:48:28 -08:00
Leonardo de Moura
53537d0684 feat(builtin/kernel): 'implication' simplification theorems 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-11 13:35:20 -08:00
Leonardo de Moura
50f281b430 feat(builtin/kernel): add eqf_intro and eqf_elim theorems 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-11 11:13:54 -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