- ((λx,y.y + x = x + y) ? ?) →
- ∀x. ((λz. x + x = z + S z) ?).
-##[ #H; #H1; #H2; #x; nnormalize in H H1 H2 ⊢ %; nauto by H, H1, H2.
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+ ((λx,y.x y = x y) ? ?) →
+ ∀x. ((λz. x + x = z + z) ?).
+##[ #H; #H1; #H2; #x; nwhd in H H1 H2 ⊢ %; nauto by H, H1, H2.
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