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An instance of the clone membership problem
by
Erhard Aichinger
Johannes Kepler University Linz, Austria
Let C be the clone on the integers that is generated by addition, subtraction, and squaring. We represent the unary functions in this clone by polynomials in Z[x] and write ○ for the composition of unary functions. Then we see that x8 = x2 ○(x2 ○x2) and 2 x5 = - x2 - ( x2 ○x2 ○x2 ) + ( x2 ○(x + x2 ○x2 ) ) lie in C. However, x5 does not lie in C.
We characterize the unary functions in C, and obtain a similar charactarization for the clone generated by {1, x, x3}.
Date received: May 13, 2008
Copyright © 2008 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cawc-61.