Different theorem provers tend to produce proof objects in different formats and this is especially the case for modal logics, where several deductive formalisms (and provers based on them) have been presented. This work falls within the general project of establishing a common specification language in order to certify proofs given in a wide range of deductive formalisms. In particular, by usi...

Three recent demands on quantifier scoping algorithms have been that they should be explicitly stated, they should be sound and complete with respect to the input sentence [Hobbs and Shieber 1987] and they should not employ a 'Free Variable Constraint' [Pereira 1989]. The first demand is for good academic practice. The second is to ask for an algorithm that generates all and only the possible s...

We describe the construction and use of a system for translating higher order logic-based speciications into programs in the higher order logic programming language Lambda Prolog. The translation improves on previous work in the eld of executing speciications by allowing formulas with quantiiers to be executed, and by permitting users to pose Prolog-style queries with free variables to be insta...

It is often alleged that high auction prices inhibit build-out. We investigate this claim under the extreme case of budget-constrained bidders. Low prices maximize overall the gains from trade. If there are n licenses, the price where the budget constraint just binds maximizes consumer surplus if the elasticity of demand is less than one plus 1/n. If demand is elastic, auctions maximize consume...

It is common to view programs as a combination of logic and control: the logic part de nes what the program must do, the control part { how to do it. The Logic Programming paradigm was developed with the intention of separating the logic from the control. Recently, extensive research has been conducted on automatic generation of control for logic programs. Only a few of these works considered t...

In this paper we describe how a combination of the classical “universal” E-unification and “rigid”E-unification, called “mixed” E-unification, can be used to efficiently handle equality in universal formula semantic tableaux, that are an extension of free variable tableaux.

Measurement error in the observed values of the variables can greatly change the output of various causal discovery methods. This problem has received much attention in multiple fields, but it is not clear to what extent the causal model for the measurement-error-free variables can be identified in the presence of measurement error with unknown variance. In this paper, we study precise sufficie...

We study a class of first-order theories whose complete quantifier-free types with one free variable either have a trivial positive part or are isolated by a positive quantifier-free formula—plus a few other technical requirements. The theory of vector spaces and the theory fields are examples. We prove the amalgamation property and the existence of a model-companion. We show that the model-com...

In a number of recent articles Timothy Williamson has built a strong case for the claim that everything necessarily exists. His argument rests on a combination of the derivability of this claim from quantificational logic, with standard modal principles and a robust understanding of the Kripke semantics for quantified modal logic. In this paper I defend a contingentist, non-Meinongian metaphysi...