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| Mirrors > Home > MPE Home > Th. List > Mathboxes > df-bj-pr2 | Structured version Visualization version GIF version | ||
| Description: Definition of the second projection of a class tuple. New usage is discouraged because the precise definition is generally unimportant compared to the characteristic properties bj-pr2eq 37017, bj-pr22val 37020, bj-pr2ex 37021. (Contributed by BJ, 6-Oct-2018.) (New usage is discouraged.) | 
| Ref | Expression | 
|---|---|
| df-bj-pr2 | ⊢ pr2 𝐴 = (1o Proj 𝐴) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | cA | . . 3 class 𝐴 | |
| 2 | 1 | bj-cpr2 37015 | . 2 class pr2 𝐴 | 
| 3 | c1o 8499 | . . 3 class 1o | |
| 4 | 3, 1 | bj-cproj 36991 | . 2 class (1o Proj 𝐴) | 
| 5 | 2, 4 | wceq 1540 | 1 wff pr2 𝐴 = (1o Proj 𝐴) | 
| Colors of variables: wff setvar class | 
| This definition is referenced by: bj-pr2eq 37017 bj-pr2un 37018 bj-pr2val 37019 bj-pr2ex 37021 | 
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