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We present a method of reasoning directly about functional programs in Second-Order Logic, based on the use of explicit second-order definitions for inductively defined data-types. Termination becomes a special case of correct typing. The formula-as-type analogy known from Proof Theory, when applied to this formalism, yields λ-expressions representing objects of inductively defined types, as well...
The purpose of this paper is to introduce a new information theory and explore its appplications. Using modern computational complexity, we study the notion of information that can be accessed through a feasible computation. In Part 1 of this paper, we lay the foundation of the theory and set up a framework for cryptography and pseudorandom number generation. In Part 2, we study the concept of trapdoor...
The first two sections of this paper motivate and outline a constructive theory of (data) types which we developed for formal program verification. The executable component of the theory provides a very high level programming language with a rich type structure. A theory of this generality appears necessary to manage complex programming and formal reasoning about it. The logical component, influencea...
In this paper we will investigate transformations that serve as tools in the design of new data structures. Specifically, we study general methods for converting static structures (in which all elements are known before any searches are performed) to dynamic structures (in which the insertion of a new element can be mixed with searches). We will see three classes of such transformations (each based...
Given a matroid, where each element has a realvalued cost and is colored red or green; we seek a minimum cost base with exactly q red elements. This is a simple case of the matroid intersection problem. A general algorithm is presented. Its efficiency is illustrated in the special case of finding a minimum spanning tree with q red edges; the time is O(m log log n + n α (n,n) log n). Efficient algorithms...
We describe a formal theory of the total correctness of parallel programs, including such heretofore theoretically incomplete properties as safety from deadlock and starvation. We present a consistent and complete set of proof rules for the total correctness of parallel programs expressed in nondeterministic form. The proof of consistency and completeness is novel in that we show that the weakest...
Fully polynomial approximation algorithms for knapsack problems are presented. These algorithms are based on ideas of Ibarra and Kim, with modifications which yield better time and space bounds, and also tend to improve the practicality of the procedures. Among the principal improvements are the introduction of a more efficient method of scaling and the use of a median-finding routine to eliminate...
Let P1 = {w ε Σ*:w = wR, |w| ≫ 1} be the set of all nontrivial palindromes over Σ. In Part I, we present a linear-time on-line recognition algorithm for P1* ("palstar") on a random-access machine with addition and uniform cost criterion. We also present a lineartime on-line recognition algorithm for P12 on a multitape Turing machine and a recognition algorithm for P12 on a two-way deterministic...
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