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Product Types

There is one library file in the directory lib_prod with the definition of (non-dependent) cross-product. As well as the basic definitions there are also theorems giving the -rule for pairs and the fact that pairing is extensional.

``` ** Module lib_prod Imports lib_eq_basics
\$prod : (Type)->(Type)->Type(prod)
\$pair1 : {A:Type}{B:Type}A->B->prod A B
\$prod_elim :
{A:Type}{B:Type}{C_prod:(prod A B)->Type}
({a:A}{b:B}C_prod (pair1 A B a b))->{z:prod A B}C_prod z
[[A:Type][B:Type][C_prod:(prod A B)->Type]
[f_pair1:{a:A}{b:B}C_prod (pair1 A B a b)][a:A][b:B]
prod_elim A B C_prod f_pair1 (pair1 A B a b)  ==>  f_pair1 a b]

Pair = ... : {A|Type}{B|Type}A->B->prod A B
prod_rec = ... : {s|Type}{t|Type}{u|Type}(s->t->u)->(prod s t)->u
prod_ind = ... :
{s|Type}{t|Type}{P:(prod s t)->Prop}({a:s}{b:t}P (Pair a b))->
{p:prod s t}P p
Fst = ... : {s|Type}{t|Type}(prod s t)->s
Snd = ... : {s|Type}{t|Type}(prod s t)->t
prod_eta = ... :
{s|Type}{t|Type}{p:prod s t}Eq p (Pair (Fst p) (Snd p))
prod_ext = ... :
{s|Type}{t|Type}{p,q:prod s t}(Eq (Fst p) (Fst q))->
(Eq (Snd p) (Snd q))->Eq p q```

Lego
Fri May 24 19:01:27 BST 1996