1461
|
1 |
(* Title: ZF/AC/WO_AC.ML
|
1123
|
2 |
ID: $Id$
|
1461
|
3 |
Author: Krzysztof Grabczewski
|
1123
|
4 |
|
|
5 |
Lemmas used in the proofs like WO? ==> AC?
|
|
6 |
*)
|
|
7 |
|
11317
|
8 |
Goal "[| well_ord(Union(A),r); 0\\<notin>A; B \\<in> A |] \
|
|
9 |
\ ==> (THE b. first(b,B,r)) \\<in> B";
|
4091
|
10 |
by (fast_tac (claset() addSEs [well_ord_imp_ex1_first RS theI RS
|
1461
|
11 |
(first_def RS def_imp_iff RS iffD1 RS conjunct1)]) 1);
|
3731
|
12 |
qed "first_in_B";
|
1123
|
13 |
|
11317
|
14 |
Goal "[| well_ord(Union(A), R); 0\\<notin>A |] ==> \\<exists>f. f:(\\<Pi>X \\<in> A. X)";
|
4091
|
15 |
by (fast_tac (claset() addSEs [first_in_B] addSIs [lam_type]) 1);
|
3731
|
16 |
qed "ex_choice_fun";
|
1123
|
17 |
|
11317
|
18 |
Goal "well_ord(A, R) ==> \\<exists>f. f:(\\<Pi>X \\<in> Pow(A)-{0}. X)";
|
4091
|
19 |
by (fast_tac (claset() addSEs [well_ord_subset RS ex_choice_fun]) 1);
|
3731
|
20 |
qed "ex_choice_fun_Pow";
|