coq - Why dependently typed languages use weak head normal form to compare for convertibility -


as far understand, dependently typed languages use weak head normal form convertibility. why so? why enough check convertibility (it seems not enough me)? can recommend read on this?

weak-head normalization sufficient , more efficient base cases.

x1 = x1 : t x1 = x2 : t, x1 ≠ x2 x1 t1 ... tn = x2 : t, x1 t1 ... tn = x2 s1 ... sn : t, x1 ≠ x2

for recursive case, function called on pairs of subterms (ti, si) anyway, there's no need reducing them eagerly.

x1 t1 ... tn = x1 s1 ... sn : t

you can read more around page 230 of advanced topics in types , programming languages edited benjamin pierce. can find lot of papers type inference , normalization pure type systems on web.

this question theoretical computer science though.


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