Consider a problem of generating a minimal threshold logic circuit for an arbitrary boolean function. This is akin to usual circuit optimization, but gates are allowed to be any threshold (linearly separable) functions.
What complexity class is this problem? I can not seem to find a paper that explicitly states it.
Zhang, Li, and Sorin Cotofana (2005) mention in the last paragraph that it is NP-complete. Is there a source that shows this? Or is it somehow obvious by analogy with conventional logic optimization?