Even though higher-order calculi for automated theorem proving are rather old, tableau calculi have not been investigated yet. This paper presents two free variable tableau calculi for higher-order logic that use higher-order uniication as the key inference procedure. These calculi diier in the treatment of the substitutional properties of equivalences. The rst calculus is equivalent in deducti...

implements a rst-order theorem prover based on free-variable semantic tableaux. It is complete, sound, and eecient.

does not allow the transmission of an arbitrary channel. In most situations a receiving process k?(k′′).Q can be alpha-converted ahead of communication so that the bound channel k′′ syntactically matches the free channel k′ in the object of the sending process [11]. The exception happens exactly when k′ is free in Q: alpha-conversion becomes impossible (for it would capture the free variable k′...

In this paper, we will present a deenability theorem for rst order logic. This theorem is very easy to state, and its proof only uses elementary tools. To explain the theorem, let us rst observe that if M is a model of a theory T in a language L, then, clearly, any deenable subset S M (i.e., a subset S = fa j M j = '(a)g deened by some formula ') is invariant under all automorphisms of M. The s...

We present a new class of second-order uniication problems, which we have called linear. We deal with completely general second-order typed uniication problems, but we restrict the set of uniiers under consideration: they instantiate free variables by linear terms, i.e. terms where any-abstractions bind one and only one occurrence of a bound variable. Linear second-order uniication properly ext...

A recent development in the theory of M-sets has paved a new means of an approach to CH. Here we further clarify the theory and form part two of our previous paper[P]. The set B i will be used to represent binary numbers. A set of positions associated with a one symbol we will denote by pos Elements of pos we will denote by p(1) j. Sets of transformations T i. A knowable set H is denoted by K(H...

Existing machines for lazy evaluation use a flat representation of environments, storing the terms associated with free variables in an array. Combined with a heap, this structure supports the shared intermediate results required by lazy evaluation. We propose and describe an alternative approach that uses a shared environment to minimize the overhead of delayed computations. We show how a shar...

It is shown how by using results from combinatory logic an applicative language, such as LISP, can be translated into a form from which all bound variables have been removed. A machine is described which can efficiently execute the resulting code. This implementation is compared with a conventional interpreter and found to have a number of advantages. Of these the most important is that program...

In this paper we investigate the role played by one aspect of context, namely encyclopedic knowledge, to the interpretation of clause arguments. We discuss cases where the assignment of a specific semantic role of a predicate to a clause argument is not determined by the grammar alone, but requires extragrammatical resources (in particular, world knowledge), and then present a formally explicit...