[adrian_b]

The " CONtinuous/disCRETE" might be useful as a mnemonic device, but you should be aware that there is no relationship between "concrete" and the "-tinuous/dis-" part.

"Con-" from "concrete" is indeed the same prefix as the "con-" from "continuous" and in both cases it means "together".

However, "-crete" from "concrete" is not the same suffix as the "-crete" from "discrete".

"-crete" from "concrete" means "grown" (it is the participle of the Latin verb "crescere", to grow), so "concrete" means "grown together".

"-crete" from "discrete" means "sifted" (it is the participle of the Latin verb "cernere", to pass through a sieve, to separate), so "discrete" means "sifted away", it comes from the same source as the verb "to discern".

[MatteoFrigo]

Knuth's "Concrete Mathematics" book claims to be a blend of CONtinuous and disCRETE mathematics. Thus, Knuth is using the suffix "-crete" incorrectly as well.

If I were you, I would send an email to Knuth reporting the error. You may receive a reward check from Knuth himself, which will give you eternal bragging rights.

[adrian_b]

I believe that Knuth knew very well the true meanings of "concrete" and "discrete" and he has just made a word play exploiting the fact that the "-crete" suffixes in the 2 words are homonyms.

However, not all his readers have understood the pun.