[astrange]

Humans have access to much better thinking abilities than art AIs do.

e.g. SD2 prompted with "not a cat" produces a cat, and "1 + 1" doesn't produce "2".

[pmarreck]

Some stable diffusion interfaces let you specify a "negative input" which will bias results away from it. It wouldn't be terribly hard to do some semantic interpretation prior to submission to the model that would turn "not a <thing>" into "negate-input <thing>"