Theorem ax13 203

Description: Axiom of Equality. Axiom scheme C12' in [Megill] p. 448 (p. 16 of the preprint). It is a special case of Axiom B8 (p. 75) of system S2 of [Tarski] p. 77.

Hypotheses

Ref	Expression
ax13.1	|- A:al
ax13.2	|- B:al
ax13.3	|- C:(al -> *)

Assertion

Ref	Expression
ax13	|- T. |= [[A = B] ==> [(CA) ==> (CB)]]

Proof of Theorem ax13

Step	Hyp	Ref	Expression
1		wtru 40	. . . . . 6 |- T.:*
2		ax13.1	. . . . . . 7 |- A:al
3		ax13.2	. . . . . . 7 |- B:al
4	2, 3	weqi 68	. . . . . 6 |- [A = B]:*
5	1, 4	wct 44	. . . . 5 |- (T., [A = B]):*
6		ax13.3	. . . . . 6 |- C:(al -> *)
7	6, 2	wc 45	. . . . 5 |- (CA):*
8	5, 7	simpr 23	. . . 4 |- ((T., [A = B]), (CA)) |= (CA)
9	1, 4	simpr 23	. . . . . 6 |- (T., [A = B]) |= [A = B]
10	6, 2, 9	ceq2 80	. . . . 5 |- (T., [A = B]) |= [(CA) = (CB)]
11	10, 7	adantr 50	. . . 4 |- ((T., [A = B]), (CA)) |= [(CA) = (CB)]
12	8, 11	mpbi 72	. . 3 |- ((T., [A = B]), (CA)) |= (CB)
13	12	ex 148	. 2 |- (T., [A = B]) |= [(CA) ==> (CB)]
14	13	ex 148	1 |- T. |= [[A = B] ==> [(CA) ==> (CB)]]

Syntax hints:   -> ht 2  *hb 3  kc 5   = ke 7  T.kt 8  [kbr 9  kct 10   |= wffMMJ2 11  wffMMJ2t 12   ==> tim 111

This theorem was proved from axioms:  ax-syl 15  ax-jca 17  ax-simpl 20  ax-simpr 21  ax-id 24  ax-trud 26  ax-cb1 29  ax-cb2 30  ax-refl 39  ax-eqmp 42  ax-ded 43  ax-ceq 46  ax-beta 60  ax-distrc 61  ax-leq 62  ax-distrl 63  ax-hbl1 93  ax-17 95  ax-inst 103

This theorem depends on definitions:  df-ov 65  df-an 118  df-im 119

This theorem is referenced by: (None)