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124 commits

Author SHA1 Message Date
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
c740d9d799 fix(builtin/num): bug in the factorial definition 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-12 10:04:32 -08:00
Leonardo de Moura
45a0dbcc34 feat(builtin/num): define fact and exp 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-12 09:51:49 -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
11a2b3016f fix(builtin/num): remove hacks for making the elaborator happy 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-10 14:05:51 -08:00
Leonardo de Moura
b7b868de85 fix(library/elaborator): bug reported by Jeremy Avigad 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-10 14:01:22 -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
273f78d1cb feat(builtin/num): prove strong induction and other theorems for num 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-09 21:09:50 -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
fd6f8b1945 refactor(builtin/num): simplify proofs using 'by simp' 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-09 15:03:45 -08:00
Leonardo de Moura
4c76f6abb9 chore(builtin/num): remove leftover 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-09 11:39:26 -08:00
Leonardo de Moura
8df7c7b02d feat(kernel/type_checker): remove fallback that expands opaque definitions in the type checker 
We should not rely on this feature. It can be quite expensive.
We invoke is_convertible in several places, in particular, if we are using overloading. For example, the frontend uses is_convertible to check which overload should be used. Thus, it will make several calls such as

   is_convertible(num, Nat)

If is_convertible starts unfolding opaque definitions, we would keep expanding num.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-09 11:31:24 -08:00
Leonardo de Moura
633ed6bb69 fix(frontends/lean/parser): bug in add_rewrite 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-09 09:46:56 -08:00
Leonardo de Moura
d6167eae32 feat(builtin/num): define add and mul 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-08 22:28:15 -08:00
Leonardo de Moura
cc4148a98d feat(builtin/num): primitive recursion theorem 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-08 22:05:57 -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
fa4b60963b feat(builtin/num): define lt predicate, and prove basic theorems 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-08 10:57:17 -08:00
Leonardo de Moura
1f3e0f7a38 chore(builtin/num): update object file 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-08 09:16:52 -08:00
Leonardo de Moura
aeaa803f9a feat(builtin): add num type (the base type that will be used to build nat, int, real) 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-08 09:12:53 -08:00
Leonardo de Moura
24528ff685 fix(library/elaborator): fix glitches in the elaborator that were forcing us to provide parameters explicitly 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-07 18:02:08 -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
db3bcdba55 refactor(builtin): move pair definition and theorems to pair.lean 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-06 09:20:52 -08:00
Leonardo de Moura
daf7075ce4 refactor(builtin/sum): use new 'have' expression to formalize optional-types 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-06 09:15:12 -08:00
Leonardo de Moura
5d698a60a7 refactor(builtin/sum): use new 'have' expression to formalize sum-types 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-06 08:59:05 -08:00
Leonardo de Moura
ba9a8f9d98 feat(frontends/lean): add 'show' expression syntax sugar 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-06 07:50:22 -08:00
Leonardo de Moura
90f5a4f813 feat(builtin/sum): cleanup, and avoid unicode character that is not available in some platforms 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-06 00:20:49 -08:00
Leonardo de Moura
c01f82aeb7 feat(builtin): add sum types 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-05 23:04:44 -08:00
Leonardo de Moura
87da23649b feat(builtin/optional): prove dichotomy and induction theorems for optional types 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-05 19:49:50 -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
f4ec874c6e refactor(builtin): remove dead module heq 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-04 14:42:28 -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
8eec289ce1 feat(kernel): add dependent pairs 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-03 16:52:49 -08:00
Leonardo de Moura
6be50f0133 refactor(builtin/heq): merge cast and heq modules 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-02-02 15:01:48 -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
bc2d504ccc feat(builtin/kernel): add rewrite rules for if-then-else 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-30 22:38:35 -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
069e5edf6b fix(library/simplifier): include flag indicating if the proof generated by simplifier is a homogenous or heterogenous equality, use flag to fix bug in the simp_tactic 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-29 12:01:01 -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
5e6c1d4904 refactor(builtin/heq): remove axiom hpiext since we don't use it anymore 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-26 13:11:17 -08:00
Leonardo de Moura
fafaa7e78e fix(library/simplifier): remove hack for handling some constants that expect an argument of type TypeU, the new approach is general 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-26 10:10:57 -08:00
Leonardo de Moura
844572c382 feat(library/simplifier): support for dependent simplification in Pi/forall expressions 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-26 00:32:05 -08:00
Leonardo de Moura
9fb3ccb4c0 feat(library/simplifier): support for dependent simplification in lambda expressions 
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
 2014-01-25 16:54:42 -08:00