@article{wirth-hilbert-epsilon-jal,
year      ={2008},
author    ={Claus-Peter Wirth},
title     ={Hilbert's epsilon as an Operator of Indefinite Committed Choice},
journal   ={J. of Applied Logic},
volume    ={6},
pages     ={287--317},
publisher ={Elsevier},
note = {\url{http://www.ags.uni-sb.de/~cp/p/epsi}, \url{http://dx.doi.org/10.1016/j.jal.2007.07.009}},
abstract  ={Hilbert and Bernays avoided overspecification of
Hilbert's $\varepsilon$-operator. They axiomatized only what was
relevant for their proof-theoretic investigations.
Semantically, this left the $\varepsilon$-operator underspecified.
After briefly
reviewing the literature on semantics of Hilbert's epsilon operator,
we propose a new semantics with the following features:
We avoid overspecification (such as right-uniqueness),
but admit indefinite choice, committed choice, and classical logics.
Moreover,
our semantics for the $\varepsilon$ simplifies proof search and
is natural in the sense that it mirrors some cases of
referential interpretation of indefinite articles in natural language.},
}