Theorem supmaxti 6969

Description: The greatest element of a set is its supremum. Note that the converse is not true; the supremum might not be an element of the set considered. (Contributed by Jim Kingdon, 24-Nov-2021.)

Hypotheses

Ref	Expression
supmaxti.ti	|- ( ( ph /\ ( u e. A /\ v e. A ) ) -> ( u = v <-> ( -. u R v /\ -. v R u ) ) )
supmaxti.2	|- ( ph -> C e. A )
supmaxti.3	|- ( ph -> C e. B )
supmaxti.4	|- ( ( ph /\ y e. B ) -> -. C R y )

Assertion

Ref	Expression
supmaxti	|- ( ph -> sup ( B , A , R ) = C )

Distinct variable groups:   u, A, v, y   u, B, v, y   u, C, v, y   u, R, v, y   ph, u, v, y

Proof of Theorem supmaxti

Dummy variable x is distinct from all other variables.

Step	Hyp	Ref	Expression
1		supmaxti.ti	. 2 |- ( ( ph /\ ( u e. A /\ v e. A ) ) -> ( u = v <-> ( -. u R v /\ -. v R u ) ) )
2		supmaxti.2	. 2 |- ( ph -> C e. A )
3		supmaxti.4	. 2 |- ( ( ph /\ y e. B ) -> -. C R y )
4		supmaxti.3	. . 3 |- ( ph -> C e. B )
5		simprr 522	. . 3 |- ( ( ph /\ ( y e. A /\ y R C ) ) -> y R C )
6		breq2 3986	. . . 4 |- ( x = C -> ( y R x <-> y R C ) )
7	6	rspcev 2830	. . 3 |- ( ( C e. B /\ y R C ) -> E. x e. B y R x )
8	4, 5, 7	syl2an2r 585	. 2 |- ( ( ph /\ ( y e. A /\ y R C ) ) -> E. x e. B y R x )
9	1, 2, 3, 8	eqsuptid 6962	1 |- ( ph -> sup ( B , A , R ) = C )

Syntax hints:   -. wn 3   -> wi 4   /\ wa 103   <-> wb 104   = wceq 1343   e. wcel 2136   E.wrex 2445   class class class wbr 3982   supcsup 6947

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 604  ax-in2 605  ax-io 699  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-10 1493  ax-11 1494  ax-i12 1495  ax-bndl 1497  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522  ax-i5r 1523  ax-ext 2147

This theorem depends on definitions:  df-bi 116  df-3an 970  df-tru 1346  df-fal 1349  df-nf 1449  df-sb 1751  df-eu 2017  df-mo 2018  df-clab 2152  df-cleq 2158  df-clel 2161  df-nfc 2297  df-ral 2449  df-rex 2450  df-reu 2451  df-rmo 2452  df-rab 2453  df-v 2728  df-sbc 2952  df-un 3120  df-sn 3582  df-pr 3583  df-op 3585  df-uni 3790  df-br 3983  df-iota 5153  df-riota 5798  df-sup 6949

This theorem is referenced by:  supsnti  6970  sup3exmid  8852  maxleim  11147  xrmaxleim  11185  supfz  13947