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Mirrors > Home > ILE Home > Th. List > pm4.54dc | Unicode version |
Description: Theorem *4.54 of [WhiteheadRussell] p. 120, for decidable propositions. One form of DeMorgan's law. (Contributed by Jim Kingdon, 2-May-2018.) |
Ref | Expression |
---|---|
pm4.54dc | DECID DECID |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dcn 746 | . . . . 5 DECID DECID | |
2 | dfandc 778 | . . . . 5 DECID DECID | |
3 | 1, 2 | syl 14 | . . . 4 DECID DECID |
4 | 3 | imp 115 | . . 3 DECID DECID |
5 | pm4.66dc 802 | . . . . 5 DECID | |
6 | 5 | adantr 261 | . . . 4 DECID DECID |
7 | 6 | notbid 592 | . . 3 DECID DECID |
8 | 4, 7 | bitrd 177 | . 2 DECID DECID |
9 | 8 | ex 108 | 1 DECID DECID |
Colors of variables: wff set class |
Syntax hints: wn 3 wi 4 wa 97 wb 98 wo 629 DECID wdc 742 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 99 ax-ia2 100 ax-ia3 101 ax-in1 544 ax-in2 545 ax-io 630 |
This theorem depends on definitions: df-bi 110 df-dc 743 |
This theorem is referenced by: pm4.55dc 846 |
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