Cylindrification

In computability theory a cylindrification is a construction that associates a cylindric numbering to each numbering. The concept was first introduced by Yuri L. Ershov in 1973.

Definition

Given a numbering \nu the cylindrification c(\nu ) is defined as

\mathrm {Domain} (c(\nu )):=\{\langle n,k\rangle |n\in \mathrm {Domain} (\nu )\}
c(\nu )\langle n,k\rangle :=\nu (i)

where \langle n,k\rangle is the Cantor pairing function. The cylindrification operation takes a relation as input of arity k and outputs a relation of arity k + 1 as follows : Given a relation R of arity K, its cylindrification denoted by c(R), is the following set {(a1,...,ak,a)|(a1,...,ak)belongs to R and a belongs to A}. Note that the cylindrification operation increases the arity of an input by 1.

Properties

References

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