theorem sbned (G: wff) {x: nat} (a: nat) (b: nat x) (c: nat):
$ G /\ x = a -> b = c $ >
$ G -> N[a / x] b = c $;
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | sbnet | A. x (x = a -> b = c) -> N[a / x] b = c |
|
| 2 | hyp e | G /\ x = a -> b = c |
|
| 3 | 2 | ialda | G -> A. x (x = a -> b = c) |
| 4 | 1, 3 | syl | G -> N[a / x] b = c |