> as lemmas

1891 J. Rayner Chess Probl. (ed. 2) 9 Waiting-move problems—i.e., those in which the first move would not lead to a mate if it were not that Black is forced to reply and thereby weaken his position.

1896 Chess Monthly May 280 There is another class of waiting problem which is usually found very interesting... A primary position which has every indication that White has but to linger without discouraging the mates as ‘set’, but..one of the mates has to be given up in exchange for another to be created.

1907 S. S. Blackburne Terms & Themes Chess Probl. 25 Block problem—Otherwise called a ‘Waiting Problem’ is one in which White's first move leads to mate after every reply of Black, in consequence of such reply.

1962 K. S. Howard One Hundred Years Amer. Two-move Chess Probl. 5 Another type [of problem]..was the complete block, or waiting-move problem, especially where some of the mating moves apparently set in the initial position were changed by the key, for which Brian Harley..coined the apt name mutate.