HomeHome Metamath Proof Explorer < Previous   Next >
Related theorems
Unicode version

Axiom ax-11o 1202
Description: Axiom ax-11o 1202 ("o" for "old") was the original version of ax-11 1180, before it was discovered (in Jan. 2007) that the shorter ax-11 1180 could replace it. It appears as Axiom scheme C15' in [Megill] p. 448 (p. 16 of the preprint). As theorem ax11o 1201 shows, ax-11o 1202 can be derived from ax-11 1180 and the other axioms; conversely, theorem ax11 1203 shows that ax-11 1180 can be derived from ax-11o 1202 and the others. An open problem is whether ax-11o 1202 can be derived from ax-11 1180 and the others when ax-16 1194 and ax-17 1190 are omitted. See ax-11 1180, ax11o 1201, and ax11 1203 for additional remarks. If we wish to identify where this axiom is needed in the absence of ax-16 1194 and ax-17 1190, we can use it in place of all references to theorem ax11o 1201 in the theorems that follow.
Assertion
Ref Expression
ax-11o |- (-. A.x x = y -> (x = y -> (ph -> A.x(x = y -> ph))))

Detailed syntax breakdown of Axiom ax-11o
StepHypRef Expression
1 vx . . . . . 6 set x
21cv 1098 . . . . 5 class x
3 vy . . . . . 6 set y
43cv 1098 . . . . 5 class y
52, 4wceq 1099 . . . 4 wff x = y
65, 1wal 950 . . 3 wff A.x x = y
76wn 2 . 2 wff -. A.x x = y
8 wph . . . 4 wff ph
95, 8wi 3 . . . . 5 wff (x = y -> ph)
109, 1wal 950 . . . 4 wff A.x(x = y -> ph)
118, 10wi 3 . . 3 wff (ph -> A.x(x = y -> ph))
125, 11wi 3 . 2 wff (x = y -> (ph -> A.x(x = y -> ph)))
137, 12wi 3 1 wff (-. A.x x = y -> (x = y -> (ph -> A.x(x = y -> ph))))
Colors of variables: wff set class
This axiom is referenced by:  ax11 1203  ax11b 1204  equs5 1205  ax11v 1249  a12study 1355  a12studyALT 1356
Copyright terms: Public domain