Now showing items 21-37 of 37

    • 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 ...
    • Quadratic Blending Surfaces 

      Hoffmann, Christoph M.; Hopcroft, John E. (Cornell University, 1985-04)
    • Reducing Multiple Object Motion Planning To Graph Searching 

      Hopcroft, John E.; Wilfong, Gordon (Cornell University, 1984-06)
      In this paper we study the motion planning problem for multiple objects where an object is a 2-dimensional body whose faces are line segments parallel to the axes of $R^{2}$ and translations are the only motions allowed. ...
    • Refinement of Hierarchies of Time Bounded Computations 

      Hartmanis, Juris; Hopcroft, John E. (Cornell University, 1968-06)
      It is shown that for any "slowly growing" time function $T(n)$ and any $\epsilon > 0$ there exists a computation which can be performed by a multitape Turing machine in time $T(n)\log^{\epsilon}T(n)$ and cannot be performed ...
    • Robust Set Operations on Polyhedral Solids 

      Hoffmann, Christoph M.; Hopcroft, John E.; Karasick, Michael S. (Cornell University, 1987-10)
      We describe an algorithm for performing regularized set operations on polyhedral solids. Robustness of this algorithm is achieved by adding symbolic reasoning as a supplemental step that compensates for possible numerical ...
    • Routing in Networks 

      Borodin, Allan B.; Hopcroft, John E. (Cornell University, 1981-11)
    • A Subexponential Algorithm for Trivalent Graph Isomorphism 

      Furst, Merrick; Hopcroft, John E.; Luks, Eugene (Cornell University, 1980-06)
    • Triangular Factorization and Inversion by Fast Matrix Multiplication 

      Bunch, James R.; Hopcroft, John E. (Cornell University, 1972-12)
      The fast matrix multiplication algorithm by Strassen is used to obtain the triangular factorization of a permutation of any non-singular matrix of order n in "greater than" C sub{1}n sup{log sub{2}7} operations, and hence ...