Description: Lemma for dath . Frequently-used utility lemma. (Contributed by NM, 15-Aug-2012)
Ref | Expression | ||
---|---|---|---|
Hypothesis | da.ps0 | |- ( ps <-> ( ( c e. A /\ d e. A ) /\ -. c .<_ Y /\ ( d =/= c /\ -. d .<_ Y /\ C .<_ ( c .\/ d ) ) ) ) |
|
Assertion | dalemddea | |- ( ps -> d e. A ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | da.ps0 | |- ( ps <-> ( ( c e. A /\ d e. A ) /\ -. c .<_ Y /\ ( d =/= c /\ -. d .<_ Y /\ C .<_ ( c .\/ d ) ) ) ) |
|
2 | simp1r | |- ( ( ( c e. A /\ d e. A ) /\ -. c .<_ Y /\ ( d =/= c /\ -. d .<_ Y /\ C .<_ ( c .\/ d ) ) ) -> d e. A ) |
|
3 | 1 2 | sylbi | |- ( ps -> d e. A ) |