Abstract: | LetA be a subset of
, and leta∉A. The setA is said to be almost semirecursive, if there is a two-place general recursive functionf such thatf(x, y)ε{x, y, a}∧({x, y}⊆A⇌f(x, y)εA) for all
. Among other facts, it is proved that ifA and
are almost semirecursive sets, thenA is a semirecursive set, and that there exists a wsr*-set that is neither a wsr-nor an almost semirecursive set.
Translated fromMatematicheskie Zametki, Vol. 66, No. 2, pp. 188–193, August, 1999. |