Definability of Leibniz Equality

Given a structure for a first-order language L, two objects of its domain can be indiscernible relative to the properties expressible in L, without using the equality symbol, and without actually being the same. It is this relation that interests us in this paper. It is called Leibniz equality. In the paper we study systematically the problem of its definibility mainly for classes of structures that are the models of some equality-free universal Horn class in an infinitary language L_κκ, where κ is an infinite regular cardinal. This revised version was published online in June 2006 with corrections to the Cover Date.     

Characterization Classes Defined without Equality

In this paper we mainly deal with first-order languages without equality and introduce a weak form of equality predicate, the so-called Leibniz equality. This equality is characterized algebraically by means of a natural concept of congruence; in any structure, it turns out to be the maximum congruence of the structure. We show that first-order logic without equality has two distinct complete semantics (fll semantics and reduced semantics) related by the reduction operator. The last and main part of the paper contains a series of Birkhoff-style theorems characterizing certain classes of structures defined without equality, not only full classes but also reduced ones.     

Reconciling nuclear risk: the impact of the Fukushima accident on comparative preferences for nuclear power in U.K. electricity generation

Polls conducted in the United Kingdom following the Fukushima nuclear accident (March 2011) indicated a fairly muted and temporary shift in public approval of nuclear power. This study investigated how: (a) comparative preferences for nuclear power in the United Kingdom might have been affected by the accident; and (b) how “supporters” of nuclear power reconciled their pro‐nuclear attitude in the wake of the disaster. Between‐subjects comparisons with a pre‐Fukushima sample revealed our post‐Fukushima sample to have comparable preferences for nuclear power. Further analysis suggested that “supporters” retained their pro‐nuclear stance in response to Fukushima by emphasizing the necessity of nuclear power in the U.K. context. The theoretical, practical and methodological implications for these findings are discussed.