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| Mirrors > Home > ILE Home > Th. List > fveq2 | GIF version | ||
| Description: Equality theorem for function value. (Contributed by NM, 29-Dec-1996.) |
| Ref | Expression |
|---|---|
| fveq2 | ⊢ (𝐴 = 𝐵 → (𝐹‘𝐴) = (𝐹‘𝐵)) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | breq1 4036 | . . 3 ⊢ (𝐴 = 𝐵 → (𝐴𝐹𝑥 ↔ 𝐵𝐹𝑥)) | |
| 2 | 1 | iotabidv 5241 | . 2 ⊢ (𝐴 = 𝐵 → (℩𝑥𝐴𝐹𝑥) = (℩𝑥𝐵𝐹𝑥)) |
| 3 | df-fv 5266 | . 2 ⊢ (𝐹‘𝐴) = (℩𝑥𝐴𝐹𝑥) | |
| 4 | df-fv 5266 | . 2 ⊢ (𝐹‘𝐵) = (℩𝑥𝐵𝐹𝑥) | |
| 5 | 2, 3, 4 | 3eqtr4g 2254 | 1 ⊢ (𝐴 = 𝐵 → (𝐹‘𝐴) = (𝐹‘𝐵)) |
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