90 citations · 111 across the 12 of their papers we have counts for
12 papers
How Much Propositional Logic Suffices for Rosser's Essential Undecidability Theorem?
Guillermo Badia, Petr Cintula, Petr Hajek +1
In this paper we explore the following question: how weak can a logic be for Rosser's essential undecidability result to be provable for a weak arithmetical theory? It is well know…
Generalization of a theorem of Zippin
Petr Hajek, Thomas Schlumprecht, Andras Zsak
We generalize and prove a result which was first shown by Zippin, and was explicitly formulated by Benyamini.
Strongly extreme points and approximation properties
Trond A. Abrahamsen, Petr Hájek, Olav Nygaard +1
We show that if is a strongly extreme point of a bounded closed convex subset of a Banach space and the identity has a geometrically and topologically good enough local approxi…
Coarse embeddings into
Petr Hajek, Thomas Schlumprecht
Let be a large enough cardinal number (assuming GCH it suffices to let ). If is a Banach space with , which admits a coarse (or uniform) emb…
The Szlenk Index of L_p(X)
Petr Hajek, Thomas Schlumprecht
We find an optimal upper bound on the values of the weak-dentability index in terms of the Szlenk index of a Banach space with separable dual. Namely, if $\…
On Modal Logics for Qualitative Possibility in a Fuzzy Setting
Petr Hajek, Dagmar Harmancová, Francesc Esteva +2
Within the possibilistic approach to uncertainty modeling, the paper presents a modal logical system to reason about qualitative (comparative) statements of the possibility (and ne…