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| Description: Define a function that extracts the second member of an ordered pair. Theorem op2nd 4086 proves that it does this. Equivalent to Definition 5.13 (ii) of [Monk1] p. 52 (compare op2nda 3452 and op2ndb 3451). The notation is the same as Monk's. |
| Ref | Expression |
|---|---|
| df-2nd |
|
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | c2nd 4078 |
. 2
| |
| 2 | vy |
. . . . 5
| |
| 3 | 2 | cv 955 |
. . . 4
|
| 4 | vx |
. . . . . . . 8
| |
| 5 | 4 | cv 955 |
. . . . . . 7
|
| 6 | 5 | csn 2409 |
. . . . . 6
|
| 7 | 6 | crn 3171 |
. . . . 5
|
| 8 | 7 | cuni 2503 |
. . . 4
|
| 9 | 3, 8 | wceq 956 |
. . 3
|
| 10 | 9, 4, 2 | copab 2666 |
. 2
|
| 11 | 1, 10 | wceq 956 |
1
|
| Colors of variables: wff set class |
| This definition is referenced by: 2ndval 4082 fo2nd 4092 f2ndres 4094 |