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| Mirrors > Home > ILE Home > Th. List > Mathboxes > bj-nndcALT | Unicode version | ||
| Description: Alternate proof of nndc 856. (Proof modification is discouraged.) (New usage is discouraged.) (Contributed by BJ, 9-Oct-2019.) |
| Ref | Expression |
|---|---|
| bj-nndcALT |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | notnot 632 |
. . 3
| |
| 2 | bj-nnor 16098 |
. . 3
| |
| 3 | 1, 2 | mpbir 146 |
. 2
|
| 4 | df-dc 840 |
. . 3
| |
| 5 | 4 | notbii 672 |
. 2
|
| 6 | 3, 5 | mtbir 675 |
1
|
| Colors of variables: wff set class |
| Syntax hints: |
| 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-in1 617 ax-in2 618 ax-io 714 |
| This theorem depends on definitions: df-bi 117 df-dc 840 |
| This theorem is referenced by: (None) |
| Copyright terms: Public domain | W3C validator |