2 papers
cs.IT2023
The Kraft--Barmpalias--Lewis-Pye lemma revisited
Alexander Shen
This note provides a simplified exposition of the proof of hierarchical Kraft lemma proven by Barmpalias and Lewis-Pye and its consequences for the oracle use in the Kučera--Gács t…
math.HO2018
Hilbert's Error?
Alexander Shen
It is well known that a center of a given circle cannot be constructed using only a straightedge and that this was proven by David Hilbert. Still it is not so clear what kind of ob…