update-spec-dom(upd;k;x) == <k, x>  dom(upd) 

latex

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clarification:

update-spec-dom(upd;k;x) == fpf-dom(product-deq(Knd;Id;KindDeq;IdDeq); <k, x>; upd) 

latex

Definitions	x  dom(f), product-deq(A;B;a;b), Knd, Id, KindDeq, IdDeq, <a, b>
FDL editor aliases	update-spec-dom