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Mirrors > Home > ILE Home > Th. List > sbft | Unicode version |
Description: Substitution has no effect on a non-free variable. (Contributed by NM, 30-May-2009.) (Revised by Mario Carneiro, 12-Oct-2016.) (Proof shortened by Wolf Lammen, 3-May-2018.) |
Ref | Expression |
---|---|
sbft |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | spsbe 1763 | . . 3 | |
2 | 19.9t 1573 | . . 3 | |
3 | 1, 2 | syl5ib 152 | . 2 |
4 | nfr 1451 | . . 3 | |
5 | stdpc4 1698 | . . 3 | |
6 | 4, 5 | syl6 33 | . 2 |
7 | 3, 6 | impbid 127 | 1 |
Colors of variables: wff set class |
Syntax hints: wi 4 wb 103 wal 1282 wnf 1389 wex 1421 wsb 1685 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-5 1376 ax-gen 1378 ax-ie1 1422 ax-ie2 1423 ax-4 1440 ax-i9 1463 ax-ial 1467 |
This theorem depends on definitions: df-bi 115 df-nf 1390 df-sb 1686 |
This theorem is referenced by: sbctt 2880 |
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