semiprojection

plural semiprojections

1. mathematicsA 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, ... xₖ) = xᵢ whenever |{x₁, x₂, ... xₖ}| < k.

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

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

   1 more example

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

   1997, Journal of the Association for Computing Machinery, page 544