theorem appendeq1d (_G: wff) (_l11 _l12 l2: nat): $ _G -> _l11 = _l12 $ > $ _G -> _l11 ++ l2 = _l12 ++ l2 $;
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | hyp _h | _G -> _l11 = _l12 |
|
2 | eqidd | _G -> l2 = l2 |
|
3 | 1, 2 | appendeqd | _G -> _l11 ++ l2 = _l12 ++ l2 |