Recent Submissions

  • Adaptive logspace reducibility and parallel time 

    Álvarez Faura, M. del Carme; Balcázar Navarro, José Luis; Jenner, Birgit (1991-11)
    External research report
    Open Access
    We discuss two notions of functional oracle for logarithmic space-bounded machines, which differ in whether there is only one oracle tape for both the query and the answer or a separate tape for the answer, which can still ...
  • The design of a parallel algorithm to solve the word problem for the free partially commutative groups 

    Gabarró Vallès, Joaquim (1991-10-15)
    External research report
    Open Access
    We develop a parallel algorithm to solve the word problem for free partially commutative groups. These groups were introduced by C. Wrathall to generalize free groups. We represent the elements of these groups as a certain ...
  • A generalization of the model of permutations for binary search trees 

    Messeguer Peypoch, Xavier (1991-09-30)
    External research report
    Open Access
    The classical model of permutations, that allows the study of consecutive insertions in BST, fails when it considers intermixed deletions and insertions (Knott paradox). Our model solves this paradox by considering the ...
  • Average-case analysis on simple families of trees using a balanced probabilistic model 

    Cases Muñoz, Rafel; Díaz Cort, Josep; Martínez Parra, Conrado (1991-02-20)
    External research report
    Open Access
    In this paper we study a balanced probability model defined over simple families of trees, which from the point of doing statistics on trees, behave in quite a different way from the uniform distribution. Using the new ...
  • Average-case analysis of equality of binary trees under the BST probability model 

    Martínez Parra, Conrado (1991-03)
    External research report
    Open Access
    In this paper a simple algorithm to test equality of binary trees currently used in symbolic computation, unification, etc. is investigated. Surprisingly enough, it takes 0(1) steps on average to decide if a given pair of ...
  • An approach to correctness of data parallel algorithms 

    Gabarró Vallès, Joaquim; Gavaldà Mestre, Ricard (1991-05)
    External research report
    Open Access
    The design of data parallel algorithms for fine-grained SIMD machines is a fundamental domain in today computer science. High standards in the specification and resolution of problems have been achieved in the sequential ...
  • The MINSUMCUT problem 

    Díaz Cort, Josep; Gibbons, Alan M.; Paterson, Michael Stewart; Torán Romero, Jacobo (1991-01)
    External research report
    Open Access
    In this paper we first present a sequential linear algorithm for an linear arrangement problem on trees, the MINSUMCUT, and then a 0(log n) time parallel algorithm for the MINSUMCUT on trees, which uses n [super 2]/(log ...
  • Functional oracle queries as a measure of parallel time 

    Álvarez Faura, M. del Carme; Balcázar Navarro, José Luis; Jenner Núñez, Birgit (1990-08)
    External research report
    Open Access
    We discuss two notions of functional oracle for logarithmic space-bounded machines, which differ in whether there is only one oracle tape for both the query and the answer or a separate tape for the answer, which can still ...
  • Deciding bisimilarity is P-complete 

    Balcázar Navarro, José Luis; Gabarró Vallès, Joaquim; Santha, Miklos (1990)
    External research report
    Open Access
    On finite labelled transition systems, the problems of deciding strong bisimilarity, observation equivalence, and observation congruence are P-complete under many-one NC-reducibility. As a consequence, algorithms for ...
  • Simulation of complicated queries by membership queries 

    Díaz Cort, Josep; Watanabe, Osamu (1990)
    External research report
    Open Access
    In this paper, we consider the following type of learning: a teacher has some set, which is called a (target) concept, in his mind, and a learner tries to obtain the representation of the concept by asking queries on it ...
  • Logarithmic space counting classes 

    Álvarez Faura, M. del Carme; Jenner Núñez, Birgit (1990-01)
    External research report
    Open Access
    We consider the logarithmic space counting classes #L, opt-L, and span-L, which are defined analogously to their polynomial time counterparts. We obtain complete functions for these three classes in terms of graphs and ...
  • Finite memory devices in CSP 

    Gabarró Vallès, Joaquim; Serna Iglesias, María José (1990-01)
    External research report
    Open Access
    It is often said that a state based approach to CSP is inadequate, however we present here some (theoretical) hints against this assertion. A new class of processes modelled by finite memory devices are considered. These ...

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