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| Mirrors > Home > MPE Home > Th. List > op1std | Structured version Visualization version GIF version | ||
| Description: Extract the first member of an ordered pair. (Contributed by Mario Carneiro, 31-Aug-2015.) |
| Ref | Expression |
|---|---|
| op1st.1 | ⊢ 𝐴 ∈ V |
| op1st.2 | ⊢ 𝐵 ∈ V |
| Ref | Expression |
|---|---|
| op1std | ⊢ (𝐶 = 〈𝐴, 𝐵〉 → (1st ‘𝐶) = 𝐴) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | fveq2 6875 | . 2 ⊢ (𝐶 = 〈𝐴, 𝐵〉 → (1st ‘𝐶) = (1st ‘〈𝐴, 𝐵〉)) | |
| 2 | op1st.1 | . . 3 ⊢ 𝐴 ∈ V | |
| 3 | op1st.2 | . . 3 ⊢ 𝐵 ∈ V | |
| 4 | 2, 3 | op1st 7994 | . 2 ⊢ (1st ‘〈𝐴, 𝐵〉) = 𝐴 |
| 5 | 1, 4 | eqtrdi 2786 | 1 ⊢ (𝐶 = 〈𝐴, 𝐵〉 → (1st ‘𝐶) = 𝐴) |
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