Let A⊆N={0,1,2,...} and β be an n-ary Boolean function. We call A a β-implicatively selector (β-IS) set if there exists an
n-ary selector general recursive function f such that (∀x
1,...,x
n)(β(χ(x
1),...,χ(x
n))=1⟹f(x
1,...,x
n)∈A), where χ is the characteristic function of A. Let F
(m), m≥1, be the family of all d
m+1
*
-IS sets, where
dm + 1* = \mathop & 1 \leqslant i < j \leqslant m + 1 (xi Úxj )d_{m + 1}^* = \mathop \& \limits_{1 \leqslant i< j \leqslant m + 1} (x_i \vee x_j )
, F
(0)=N, and F
(∞) is the class of all subsets in N. The basic result of the article says that the family of all β-IS sets coincides with one
of F
(m), m≥0, or F
(∞), and, moreover, the inclusions F
(0)⊂F
(1)⊂...⊂F
(∞) hold.
Translated fromAlgebra i Logika, Vol. 35, No. 2, pp. 145–153, March–April, 1996.