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An Isaac Newton Institute Programme

Logic and Algorithms

Choiceless Polynomial Time

Author: David Richerby (Athens)


We will introduce the choiceless polynomial time (CPT) model of computation, due to Blass, Gurevich and Shelah. With the addition of a counting operator, CPT is known to be more powerful than inflationary fixed-point logic with counting (IFP+C) while still being contained in polynomial time. Blass et al give a number of candidate problems for separating CPT with counting from P, including the query due to Cai, Fuerer and Immerman that separates IFP+C from P. We show that this particular query is definable in CPT, even without counting.