9 citations · 18 across the 12 of their papers we have counts for
16 papers
Feedback computability on Cantor space
Nathanael L. Ackerman, Cameron E. Freer, Robert S. Lubarsky
We introduce the notion of feedback computable functions from to , extending feedback Turing computation in analogy with the standard notion of computability for functio…
Realizability Models Separating Various Fan Theorems
Robert S. Lubarsky, Michael Rathjen
We develop a realizability model in which the realizers are the reals not just Turing computable in a fixed real but rather the reals in a countable ideal of Turing degrees. This i…
Separating the Fan Theorem and Its Weakenings
Robert S. Lubarsky, Hannes Diener
Varieties of the Fan Theorem have recently been developed in reverse constructive mathematics, corresponding to different continuity principles. They form a natural implicational h…
Principles Weaker than BD-N
Robert S. Lubarsky, Hannes Diener
BD-N is a weak principle of constructive analysis. Several interesting principles implied by BD-N have already been identified, namely the closure of the anti-Specker spaces under…
Walker's cancellation theorem
Robert Lubarsky, Fred Richman
Walker's cancellation theorem says that if B+Z is isomorphic to C+Z in the category of abelian groups, then B is isomorphic to C. We construct an example in a diagram category of a…
On the Failure of BD-N and BD, and an Application to the Anti-Specker Property
Robert Lubarsky
We give the natural topological model for the failure of BD-N, and use it to show that the closure of spaces with the anti-Specker property under product does not imply BD-N. Also,…