Theorem dom3 6778

Description: A mapping (first hypothesis) that is one-to-one (second hypothesis) implies its domain is dominated by its codomain. C and D can be read C ( x ) and D ( y ), as can be inferred from their distinct variable conditions. (Contributed by Mario Carneiro, 20-May-2013.)

Hypotheses

Ref	Expression
dom2.1	|- ( x e. A -> C e. B )
dom2.2	|- ( ( x e. A /\ y e. A ) -> ( C = D <-> x = y ) )

Assertion

Ref	Expression
dom3	|- ( ( A e. V /\ B e. W ) -> A ~<_ B )

Distinct variable groups:   x, y, A   x, B, y   y, C   x, D   x, V, y   x, W, y

Allowed substitution hints:   C( x)   D( y)

Proof of Theorem dom3

Step	Hyp	Ref	Expression
1		dom2.1	. . 3 |- ( x e. A -> C e. B )
2	1	a1i 9	. 2 |- ( ( A e. V /\ B e. W ) -> ( x e. A -> C e. B ) )
3		dom2.2	. . 3 |- ( ( x e. A /\ y e. A ) -> ( C = D <-> x = y ) )
4	3	a1i 9	. 2 |- ( ( A e. V /\ B e. W ) -> ( ( x e. A /\ y e. A ) -> ( C = D <-> x = y ) ) )
5		simpl 109	. 2 |- ( ( A e. V /\ B e. W ) -> A e. V )
6		simpr 110	. 2 |- ( ( A e. V /\ B e. W ) -> B e. W )
7	2, 4, 5, 6	dom3d 6776	1 |- ( ( A e. V /\ B e. W ) -> A ~<_ B )

Syntax hints:   -> wi 4   /\ wa 104   <-> wb 105   = wceq 1353   e. wcel 2148   class class class wbr 4005   ~<_ cdom 6741

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 709  ax-5 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-10 1505  ax-11 1506  ax-i12 1507  ax-bndl 1509  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535  ax-13 2150  ax-14 2151  ax-ext 2159  ax-sep 4123  ax-pow 4176  ax-pr 4211  ax-un 4435

This theorem depends on definitions:  df-bi 117  df-3an 980  df-tru 1356  df-nf 1461  df-sb 1763  df-eu 2029  df-mo 2030  df-clab 2164  df-cleq 2170  df-clel 2173  df-nfc 2308  df-ral 2460  df-rex 2461  df-rab 2464  df-v 2741  df-sbc 2965  df-csb 3060  df-un 3135  df-in 3137  df-ss 3144  df-pw 3579  df-sn 3600  df-pr 3601  df-op 3603  df-uni 3812  df-br 4006  df-opab 4067  df-mpt 4068  df-id 4295  df-xp 4634  df-rel 4635  df-cnv 4636  df-co 4637  df-dm 4638  df-rn 4639  df-res 4640  df-ima 4641  df-iota 5180  df-fun 5220  df-fn 5221  df-f 5222  df-f1 5223  df-fv 5226  df-dom 6744

This theorem is referenced by: (None)