Albert Visser

collaborators

3 papers

math.LO2026

On a Theorem by Bezboruah & Shepherdson

Albert Visser

We discuss an incompleteness result proven by Bezboruah and Shepherdson. This result tells us that the weak theory $PA^{-}$ does not prove the consistency of any theory (under…

math.LO2026

On a Question of Hamkins'

Albert Visser

Joel Hamkins asks whether there is a $I^_{1}^{0}$ -formula $I ¨ (x)$ such that $I ¨ (┌ I ¨ ┐)$ is independent over $PA + I ¨ $ , if this theory is consistent, where this co…

math.LO2026

Extensional Independence

Taishi Kurahashi, Albert Visser

Joel Hamkins asks whether there is a $I^_{1}^{0}$ -formula $I ¨ (x)$ such that $I ¨ (I ¨ )$ is independent over $PA + I ¨ $ , if this theory is consistent, where this construction is extensi…