Now showing items 11-30 of 37

    • Independence Results in Computer Science 

      Hartmanis, Juris; Hopcroft, John E. (Cornell University, 1976-12)
      In this note we show that instances of problems which appear naturally in computer science cannot be answered in formalized set theory. We show, for example, that some relativized versions of the famous P = NP problem ...
    • A Linear Algorithm for Testing Equivalence of Finite Automata 

      Hopcroft, John E.; Karp, R. M. (Cornell University, 1971-12)
      An algorithm is given for determining if two finite automata with start states are equivalent. The asymptotic running time of the algorithm is bounded by a constant times the product of the number of states of the larger ...
    • A Linear List Merging Algorithm 

      Hopcroft, John E.; Ullman, Jeffrey D. (2008-05-14)
      A linear list merging algorithm and its analysis is presented. Starting with n lists, each containing a single element, the algorithm will execute an arbitrary sequence of requests to merge lists and to find the name of ...
    • A Linear Time Algorithm for the Generalized Consecutive Retrieval Problem 

      Dietz, Paul F.; Furst, Merrick; Hopcroft, John E. (Cornell University, 1979-07)
      THe Generalized Consecutive Retrieval Problem (GCRP) is to find a directed tree on $n$ records in which each of $k$ subsets forms a directed path. The problem arises in organizing information for efficient retrieval. A ...
    • Merging on Parallel Models of Computation 

      Borodin, Allan B.; Hopcroft, John E. (Cornell University, 1981-09)
      A variety of models have been proposed for the study of synchronous parallel computation. We review these models and study further some prototype problems. Within a spectrum of shared memory models, we show that $\log ...
    • Movement Problems for 2-Dimensional Linkages 

      Hopcroft, John E.; Joseph, Deborah A.; Whitesides, Sue H. (Cornell University, 1982-08)
    • A Note on Cryptography and NP$\cap$ CoNP-P 

      Brassard, Giles; Fortune, Steven; Hopcroft, John E. (Cornell University, 1978-04)
      Diffie and Hellman [2] propose the use of the exponential function in a finite field for cryptographic purposes. The proposal is based on the conjecture that the inverse function, the logarithm, is not feasibly computable. ...
    • A Note on Rabin's Nearest-Neighbor Algorithm 

      Fortune, Steven; Hopcroft, John E. (Cornell University, 1978-04)
      Rabin has proposed a probabilistic algorithm for finding the closest pair of a set of points in Euclidean space. His algorithm is asymtomatically linear whereas the best of the known deterministic algorithms take order ...
    • On Edge Coloring Bipartite Graphs 

      Cole, Richard; Hopcroft, John E. (Cornell University, 1980-11)
    • On Minimizing the Number of Multiplications Necessary for Matrix Multiplication 

      Hopcroft, John E.; Kerr, Leslie Robert (Cornell University, 1969-09)
      This paper develops an algorithm to multiply a px2 matrix by a 2xn matrix in $\lceil (3pn+max(n,p))/2 \rceil$ multiplications for matrix multiplication without commutativity. The algorithm minimizes the number of multiplications ...
    • On Planar Point Matching Under Affine Transformation 

      Hopcroft, John E.; Huttenlocher, Daniel P. (Cornell University, 1989-04)
    • On the Equivalence and Containment Problems for Context-Free Languages 

      Hopcroft, John E. (Cornell University, 1968-06)
      Let $G$ and $G_{0}$ be context-free grammars. Necessary and sufficient conditions on $G_{0}$ are obtained for the decidability of $L(G_{0}) \subseteq L(G)$. It is also shown that it is undecidable for which $G_{0},L(G) ...
    • On the Motion of Objects in Contact 

      Hopcroft, John E.; Wilfong, Gordon (Cornell University, 1984-05)
      There is an increasing use of computers in the design, manufacture and manipulation of physical objects. An important aspect of reasoning about such actions concerns the motion of objects in contact. The study of problems ...
    • On the Movement of Robot Arms in Two Dimensional Bounded Regions 

      Hopcroft, John E.; Joseph, Deborah A.; Whitesides, Sue H. (Cornell University, 1982-04)
      The classical mover's problem is the following: can a rigid object in 3-dimensional space be moved from one given position to another while avoiding obstacles? It is known that a more general version of this problem ...
    • On the Reachability Problem for 5-Dimensional Vector Addition Systems 

      Hopcroft, John E.; Pansiot, J. (Cornell University, 1976-06)
      The reachability set for vector addition systems of dimension less than or equal to five are shown to be effectively computable semilinear sets. Thus reachability, equvalence and containment are decidable up to dimension ...
    • On Time Versus Space 

      Hopcroft, John E.; Paul, Wolfgang J.; Valiant, Leslie (Cornell University, 1975-12)
      It is shown that every deterministic multitape Turing machine of time complexity t(n)/log t(n). Consequently, for tape constructable t(n), the class of languages recognizable by multitape Turing machines of time complexity ...
    • An Overview of the Theory of Computational Complexity 

      Hartmanis, Juris; Hopcroft, John E. (Cornell University, 1970-04)
      The purpose of this paper is to outline the theory of computational complexity which has emerged as a comprehensive theory during the last decade. This theory is concerned with the quantitative aspects of computations and ...
    • A Paradigm for Robust Geometric Algorithms 

      Hopcroft, John E.; Kahn, Peter J. (Cornell University, 1989-10)
      No abstract is available.
    • Polynomial-Time Algorithms for Permutation Groups 

      Furst, Merrick; Hopcroft, John E.; Luks, Eugene (Cornell University, 1980-10)
      A permutation group on n letters may always be represented by a small set of generators, even though its size may be exponential in n. We show that it is practical to use such a representation since many problems such ...
    • The Potential Method for Blending Surfaces and Corners 

      Hoffmann, Christoph M.; Hopcroft, John E. (Cornell University, 1985-09)
      We survey the potential method for blending implicit algebraic surfaces, summarizing and extending work previously reported. The method is capable of deriving blends for pairs of algebraic surfaces, and is guaranteed to ...