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Mirrors > Home > MPE Home > Th. List > suceq | Structured version Visualization version GIF version |
Description: Equality of successors. (Contributed by NM, 30-Aug-1993.) (Proof shortened by Andrew Salmon, 25-Jul-2011.) |
Ref | Expression |
---|---|
suceq | ⊢ (𝐴 = 𝐵 → suc 𝐴 = suc 𝐵) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id 22 | . . 3 ⊢ (𝐴 = 𝐵 → 𝐴 = 𝐵) | |
2 | sneq 4568 | . . 3 ⊢ (𝐴 = 𝐵 → {𝐴} = {𝐵}) | |
3 | 1, 2 | uneq12d 4094 | . 2 ⊢ (𝐴 = 𝐵 → (𝐴 ∪ {𝐴}) = (𝐵 ∪ {𝐵})) |
4 | df-suc 6257 | . 2 ⊢ suc 𝐴 = (𝐴 ∪ {𝐴}) | |
5 | df-suc 6257 | . 2 ⊢ suc 𝐵 = (𝐵 ∪ {𝐵}) | |
6 | 3, 4, 5 | 3eqtr4g 2804 | 1 ⊢ (𝐴 = 𝐵 → suc 𝐴 = suc 𝐵) |
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