semiprojection

English

Noun

semiprojection (plural semiprojections)

1. (mathematics) A function f of rank k, where k is greater than or equal to three, such that for some index i between one and k (inclusive), f(x₁, x₂, ... x_k) = x_i whenever |{x₁, x₂, ... x_k}| < k.
   • 1997, Journal of the Association for Computing Machinery, page 544:

     We now show that closure under a semiprojection operation is not in general a sufficient condition for tractability.

   • 2012, Janos Aczel, Aggregating clones, colors, equations, iterates, numbers, and tiles, page 13:

     Let f be the semiprojection defined by the bitransitive relation R. Then [f] is a minimal clone.