| CS-98-31 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Title | Quickly Excluding K(2,r) from Planar Graphs | ||||||||
| Authors | D.M. Thilikos | ||||||||
| Abstract | We prove that any planar graph that does not contain $K_{2,r}$ as a minor has treewidth $\leq r+2$. | ||||||||
| Date | December 1998 | ||||||||
| Comments | Submitted to: Journal of Combinatorial Theory Series B. | ||||||||
| Report | Quickly Excluding K(2,r) from Planar Graphs (PDF) | 
      Compressed
      PostScript: Quickly Excluding K(2,r) from Planar Graphs (PS.Z)  | |||||||
| CS-98-30 | ||||
|---|---|---|---|---|
| Title | Convergence of Lattice and PDE Methods for Pricing Asian Options | |||
| Authors | P.A. Forsyth, K.R. Vetzal and R. Zvan | |||
| Abstract | In a recent article, the authors stated that the lattice based Forward Shooting Grid (FSG) method was convergent for Asian options even if nearest lattice point interpolation is used, and independent of any relationship between the grid quantization parameter (for the spacing of the nodal averages), and the timestep size. However, a more detailed analysis of the propagation of interpolation error reveals a problem. A worst case error analysis shows that the error may be large as the number of timesteps becomes large. We demonstrate that the worst case error is indeed attained in some numerical examples. In contrast, the Hull and White method is convergent provided that the node spacing in the average direction is selected appropriately as $\Delta t \rightarrow 0$. It is a also a straightforward matter to show that partial differential equation (PDE) based methods are also convergent. Numerical examples comparing convergence for all three techniques are presented. | |||
| Date | December 1998 | |||
| Comments | This paper has been submitted to mathematical finance. | |||
| Report | CS-98-30 (PDF) | 
      Compressed
      PostScript: CS-98-30 (PS.Z)  | ||
| CS-98-29 | ||||
|---|---|---|---|---|
| Title | On the Scalability of Monitoring and Debugging Distributed Computations: Vector-Clock Size | |||
| Authors | P.A.S. Ward | |||
| Abstract | The vector-clock size necessary to characterize causality in an arbitrary distributed computation is equal to the number of processes in that computation. However, in practice the vector-clock size necessary may be much smaller. The vector-clock size is not strictly bounded by the number of processes, but rather by the dimension of the partial order induced by the computation. While the dimension theoretically can be as large as the number of processes, in practice we have found it to be much smaller. In this paper we quantify exactly how small the dimension, and hence the vector-clock size required, is over a range of typical distributed computations. We have found that typical distributed computations, with as many as 300 processes, have dimension less than 10. In order to achieve this quantification we developed several novel theorems and algorithms which we also describe. | |||
| Date | December 1998 | |||
| Comments | 
        Published
        in
        ICPP'99
        under
        the
        title:
         An Offline Algorithm for Dimension-Bound Analysis  | |||
| Report | On the Scalability of Monitoring and Debugging Distributed Computations: Vector-Clock Size (PDF) | 
      Compressed
      PostScript: On the Scalability of Monitoring and Debugging Distributed Computations: Vector-Clock Size (PS.Z)  | ||
| CS-98-28 | ||||
|---|---|---|---|---|
| Title | Stratified Wavelength Clusters for Efficient Spectral | |||
| Authors | G.F. Evans and M.D. McCool | |||
| Abstract | 
      Wavelength
      dependent
      Monte
      Carlo
      rendering
      can
      correctly
      and
      generally
      capture
      effects
      such
      as
      spectral
      caustics
      (rainbows)
      and
      chromatic
      abberation.
      It
      also
      improves
      the
      colour
      accuracy
      of
      reflectance
      models
      and
      of
      illumination
      effects
      such
      as
      colour
      bleeding
      and
      metamerism. The stratified wavelength clustering (SWC) strategy carries several wavelength stratified radiance samples along each light transport path. The cluster is split only if a specular refraction at the surface of a dispersive material is encountered along the path. The overall efficiency of this strategy is high since the fraction of clusters that need to be split in a typical scene is low, and also because specular dispersion tends to decrease the source colour variance, offseting the increased amortized cost of generating each path.  | |||
| Date | November 1998 | |||
| Comments | 
      This
      report
      was
      typeset
      in
      LaTeX,
      but
      has
      been
      converted
      to
      PostScript
      at
      600dpi.
      It
      contains
      colour
      images,
      but
      can
      be
      printed
      on
      a
      high-resolution
      black
      and
      white
      laser
      printer
      with
      halftoning.
      Obviously
      colour
      is
      important
      in
      this
      work,
      but
      only
      the
      last
      page
      need
      be
      printed
      in
      colour. There is a website at http://www.cgl.uwaterloo.ca/Projects/rendering/ which contains more information on this and other rendering projects in CGL. This report has been submitted to Graphics Interface '99.  | |||
| Report | Stratified Wavelength Clusters for Efficient Spectral (PDF) | 
      Compressed
      PostScript: Stratified Wavelength Clusters for Efficient Spectral (GZIP)  | ||
| CS-98-27 | ||||
|---|---|---|---|---|
| Title | Two-Phase Clustering of Large Datasets | |||
| Authors | N.J.-K. Khazjvi and K. Salem | |||
| Abstract | 
      This
      paper
      addresses
      the
      problem
      of
      single-pass
      clustering
      of
      large,
      multi-dimensional
      datasets.
      A
      general
      two-phase
      approach
      to
      this
      problem
      is
      defined.
      In
      the
      first
      phase,
      an
      in-memory
      summary
      of
      the
      data
      set
      is
      constructed
      using
      a
      single
      pass
      through
      the
      data.
      The
      second
      phase
      then
      uses
      any
      clustering
      algorithm
      to
      cluster
      the
      summary
      data.
      Most
      clustering
      algorithms
      for
      large
      datasets
      are
      two-phase. Two techniques for producing in-memory summaries are compared. The first is based on a previously-proposed data structure called a cluster-feature tree, or CF-tree. The second, simpler technique uses random sampling. Experiments with skewed artificial data sets are used to show that sampling produces clusters that are at least as accurate as those produced with CF-trees, and that sampling is much faster. An important issue when sampling is the sample size, which determines the amount of memory required during the first phase of two-phase clustering. It also controls a trade-off between clustering time and and clustering accuracy. This tradeoff is quantified, and guidelines for sample size selection are suggested.  | |||
| Date | November 1998 | |||
| Report | Two-Phase Clustering of Large Datasets (PDF) | 
      Compressed
      PostScript: Two-Phase Clustering of Large Datasets (PS.Z)  | ||
| CS-98-26 | ||||
|---|---|---|---|---|
| Title | A Computational Model of lexical cohesion analysis and its application to the evaluation of text coherence | |||
| Authors | Marzena H. Makuta | |||
| Abstract | 
         In this thesis, we discuss how to apply the analysis of lexical cohesion in texts to the problem of evaluating text coherence. We have two objectives. The first one is to create a computational model to represent the lexical cohesion of a given text. In order to store this information we design a new data structure — the lexical graph — with lexical items as nodes and lexical relations between those items, such as synonymy, represented as arcs. This structure is particularly suitable for short texts. For longer texts, we propose a different but related data structure, the collapsed lexical graph, with paragraphs as nodes and lexical bonds as arcs. In addition, we discuss the role of a domain-specific thesaurus as a resource for determining the lexical relations for the representation. Next, we show how to apply our model for the representation of cohesion to the problem of evaluating text coherence, for texts of arbitrary length. We present hypotheses on how to detect the sites of possible coherence problems based on the cohesion information supplied by our model. We also describe an experiment which we conducted to confirm the validity of our model, comparing the predictions of the model with text evaluations performed by human judges. In addition, we discuss the areas of application for the model, commenting on how detecting sites of possible incoherence can be of value to problems such as text critiquing and second language learning and proposing new improvements to automated procedures such as natural language generation and machine translation. The thesis therefore provides important new research within the field of computational linguistics on how a representation of the cohesion of a text provides an understanding of the coherence of that text.  | |||
| Report | A Computational Model of lexical cohesion analysis and its application to the evaluation of text coherence (PDF) | 
      Compressed
      PostScript: A Computational Model of lexical cohesion analysis and its application to the evaluation of text coherence (PS.Z)  | ||
| CS-98-25 | ||||
|---|---|---|---|---|
| Title | A Computational Model of Turn-taking in Discourse | |||
| Authors | T. Donaldson | |||
| Abstract | This thesis presents a computational model for turn-taking applicable to dialog-based interactive systems. A general, three-part model of the internal architecture of a turn-taking agent is presented, accounting for why an agent should take a turn, what it should contribute, and when it should act. For deciding what to say, the next-action constraint optimization problem is developed, which allows an agent to order multiple goals using an interruptible local search algorithm sensitive to the time-constraints imposed by dynamic dialog environments. For deciding when to speak, a formal account of turn-taking is given, based on the situation calculus, and accompanied by a state-based algorithm that tells an agent when it should take a turn based in part on the status of its processing. Two prototype implementations of course-advising systems are presented, to illustrate how interactive systems can be analyzed using a checklist for system designers derived from the turn-taking model. In developing a computational model for turn-taking, this thesis shows how to bring models for written discourse one step closer to spoken dialog, and thus advances the state of the art in natural language discourse theory and in natural language generation. | |||
| Date | December 1998 | |||
| Comments | PhD thesis on computational discourse, turn-taking in particular | |||
| Report | A Computational Model of Turn-taking in Discourse (PDF) | 
      Compressed
      PostScript: A Computational Model of Turn-taking in Discourse (PS.Z)  | ||
| CS-98-24 | ||||
|---|---|---|---|---|
| Title | Multi-Agent Systems for Internet Information Retrieval using Natural Language Processing | |||
| Authors | V. Keselj | |||
| Abstract | 
      In
      the
      context
      of
      the
      vast
      and
      still
      rapidly
      expanding
      Internet,
      the
      problem
      of
      Internet
      information
      retrieval
      becomes
      more
      and
      more
      important.
      Although
      the
      most
      popular
      at
      the
      moment,
      the
      keyword-based
      search
      engine
      is
      just
      one
      component
      in
      a
      complex
      software
      mosaic
      that
      needs
      to
      be
      further
      developed
      in
      order
      to
      provide
      a
      more
      efficient
      and
      scalable
      solution. This report will argue that the multi-agent approach is a viable methodology for this task. The main issue is how the natural language processing could be used in it, as well as why it should be used. Two implementations and their theoretical foundations are presented: One is the natural language parser generator NL PAGE, which produces parsers in C or Java; and, the other one is the communication part of the multi-agent framework MIN. The higher levels of the framework are also discussed and a simple implementation of a multi-agent system is presented.  | |||
| Date | September 1998 | |||
| Comments | This technical report is a reprint of my MMath thesis, finished in September 1997. | |||
| Report | Multi-Agent Systems for Internet Information Retrieval using Natural Language Processing (PDF) | 
      Compressed
      PostScript: Multi-Agent Systems for Internet Information Retrieval using Natural Language Processing (PS.Z)  | ||
| CS-98-23 | ||||
|---|---|---|---|---|
| Title | User's Manual Elem2 Rule Induction System | |||
| Authors | A. An and N. Cercone | |||
| Date | September 1998 | |||
| Report | User's Manual Elem2 Rule Induction System (DOC) | |||
| CS-98-22 | ||||
|---|---|---|---|---|
| Title | The Role of Morphology in Machine Translation | |||
| Authors | B. Hui | |||
| Abstract | Although the study of machine translation has been around for a long time, it has not always taken advantage of the existing linguistic knowledge. This observation leads to the objective of this paper: to apply various aspects of morphology to machine translation (MT). We first review basic approaches in MT and common phenomena in morphological theory. Then we turn to a discussion on four major problems of MT and how morphological analysis can result in more accurate solutions. The problems we study in this paper are the applicability of stemming in MT, the effects of lexical ambiguity, the structure of the lexicon, and the process of lexical choice in generation. A new proposal using cross-language word hierarchies was made to tackle the problem of translational ambiguity in MT. We sampled data from Japanese and Cantonese and illustrated how our approach can be used in understanding and generation. Since the analysis was based on limited data, the results are preliminary and need to be fine tuned before a sound theory can be integrated into an MT system. | |||
| Date | July 1998 | |||
| Report | The Role of Morphology in Machine Translation (PDF) | 
      Compressed
      PostScript: The Role of Morphology in Machine Translation (PS.Z)  | ||
| CS-98-21 | ||||
|---|---|---|---|---|
| Title | An efficient algorithm for computing the i'th letter of Phi^n(a) | |||
| Authors | J. Shallit and D. Swart | |||
| Abstract | Let Sigma be a finite alphabet, and let $Phi:Sigma* ->Sigma* be a homomorphism, i.e., a mapping satisfying Phi(xy) = Phi(x)Phi(y) for all x and y in Sigma*. Let a be a letter in Sigma, and let i <= 1, n <= 0 be integers. We give the first efficient algorithm for computing the i'th letter of Phi^n(a). Our algorithm runs in time polynomial in the size of the input, i.e., polynomial in log n, log i, and the description size of Phi. Our algorithm can be easily modified to give the distribution of letters in the prefix of length i of Phi^n(a). There are applications of our algorithm to computer graphics and biological modelling. | |||
| Date | July 1998 | |||
| Comments | Submitted to: Symposium On Discrete Algorithms (SODA) 1998 | |||
| Report | An efficient algorithm for computing the i'th letter of Phi^n(a) (PDF) | 
      Compressed
      PostScript: An efficient algorithm for computing the i'th letter of Phi^n(a) (GZIP)  | ||
| CS-98-19 | ||||
|---|---|---|---|---|
| Title | Animated Surface Pasting | |||
| Authors | C. Tsang | |||
| Abstract | Surface pasting is a composition method in which a feature surface is attached to a base surface to provide details on the underlying surface. In computer animation, a lot of time is spent modelling and surface pasting is a modelling method that can quickly and easily model faces and other objects with small details. Thus, surface pasting may be a useful animation technique because it reduces the modelling time. However, it is unclear whether pasted surfaces will have problems such as distortion in animation. In this thesis, surface pasting was combined into the animation process to see how pasted surfaces behave in animation. In general, while surface pasting behaved as desired in animation, there are some situations where it behaves poorly. Most of these bad situations can be avoided or corrected by the animator. | |||
| Date | July 1998 | |||
| Report | Animated Surface Pasting (PDF) | 
      Compressed
      PostScript: Animated Surface Pasting (PS.Z)  | ||
| CS-98-17 | ||||
|---|---|---|---|---|
| Title | Planar Drawings of Origami Polyhedra | |||
| Authors | E.D. Demaine and M.L. Demaine | |||
| Abstract | We present a new infinite class of polyhedra based on a class of origami bases that we have developed. To understand these polyhedra and their underlying bases, we examine drawings of their graphs. We present an elegant linear-time algorithm to find a straight-line planar drawing. It displays a recursive structure in the polyhedra that may lead to interesting fractals. We introduce a ``zoom'' feature that allows one to interactively explore the details of the graph while displaying this recursive structure. | |||
| Date | August 1998 | |||
| Comments | 
      A
      two-page
      abstract
      of
      this
      paper
      appeared
      in
      the
      Proceedings
      of
      the
      6th
      Symposium
      on
      Graph
      Drawing,
      Lecture
      Notes
      in
      Computer
      Science,
      volume
      1547,
      Montreal,
      Quebec,
      Canada,
      August
      13-15,
      1998,
      pages
      438-440. Feel free to contact us.  | |||
| Report | Planar Drawings of Origami Polyhedra (PDF) | 
      Compressed
      PostScript: Planar Drawings of Origami Polyhedra (PS.Z)  | ||
| CS-98-15 | ||||
|---|---|---|---|---|
| Title | Cubic precision Clough-Tocher interpolation | |||
| Authors | S. Mann | |||
| Abstract | The standard Clough-Tocher split-domain scheme constructs a surface element with quadratic precision. In this paper, I will look at methods for improving the degrees of freedom in Clough-Tocher schemes. In particular, I will discuss modifications to the cross-boundary construction that improve the interpolant from quadratic precision to cubic precision. | |||
| Date | July 1998 | |||
| Report | Cubic precision Clough-Tocher interpolation (PDF) | 
      Compressed
      PostScript: Cubic precision Clough-Tocher interpolation (PS.Z)  | ||
| CS-98-14 | ||||
|---|---|---|---|---|
| Title | Multiresolution Curve and Surface Representation by Reversing and Subdivision Rules | |||
| Authors | F.F. Samavati and R.H. Bartels | |||
| Date | June 1998 | |||
| Report | Multiresolution Curve and Surface Representation by Reversing and Subdivision Rules (PDF) | 
      Compressed
      PostScript: Multiresolution Curve and Surface Representation by Reversing and Subdivision Rules (GZIP)  | ||
| CS-98-13 | ||||
|---|---|---|---|---|
| Title | Reasoning about Non-Key Uniqueness Constraints on Object Schema | |||
| Authors | V.L. Khizder and G. Weddell | |||
| Abstract | 
      Uniqueness
      constraints
      such
      as
      keys
      and
      functional
      dependencies
      in
      the
      relational
      model
      are
      a
      core
      concept
      in
      information
      systems
      technology.
      In
      this
      technical
      report,
      we
      identify
      a
      boundary
      between
      efficient
      and
      intractable
      kinds
      of
      uniqueness
      constraints
      suitable
      for
      object
      relational
      data
      models.
      The
      efficient
      subclass
      of
      the
      constraints
      is
      a
      strict
      generalization
      of
      both
      keys
      and
      relational
      functional
      dependencies.
      We
      present
      a
      complete
      and
      efficient
      procedure
      that
      solves
      the
      membership
      problem
      for
      this
      subclass.
      To
      motivate
      our
      results,
      we
      review
      some
      applications
      of
      our
      procedure
      in
      query
      optimization
      and
      schema
      evaluation. In addition, we formulate the problem in terms of a description logic (DL). DLs are a family of languages for knowledge representation that have many applications in information systems technology. Thus, in addition to enhancing earlier work on uniqueness constraints, we integrate the results in the larger body of work on DLs.  | |||
| Date | June 1998 | |||
| Report | Reasoning about Non-Key Uniqueness Constraints on Object Schema (DOC) | Reasoning about Non-Key Uniqueness Constraints on Object Schema (ZIP) | ||
| CS-98-11 | ||||
|---|---|---|---|---|
| Title | Symmetries and First Order ODE Patterns | |||
| Authors | E.S. Cheb-Terrab, and A.D. Roche | |||
| Abstract | A scheme for determining symmetries for certain families of first order ODEs, without solving any differential equations, and based mainly in matching an ODE to patterns of invariant ODE families, is presented. The scheme was implemented in Maple, in the framework of the {\it ODEtools} package and its ODE-solver. A statistics of the performance of this approach in solving the first order ODE examples of Kamke's book is shown. | |||
| Date | April 1998 | |||
| Comments | Submitted to: Computer Physics Communications | |||
| Report | Symmetries and First Order ODE Patterns (PDF) | 
      Compressed
      PostScript: Symmetries and First Order ODE Patterns (PS.Z)  | ||
| CS-98-10 | ||||
|---|---|---|---|---|
| Title | Integrating Factors and ODE Patterns | |||
| Authors | E.S. Cheb-Terrab and A.D. Roche | |||
| Abstract | A systematic algorithm for building integrating factors of the form mu(x,y') or mu(y,y') for non-linear second order ODEs is presented. When such an integrating factor exists, the scheme returns the integrating factor itself, without solving any differential equations. The scheme was implemented in Maple, in the framework of the ODEtools package and its ODE-solver. A comparison between this implementation and other computer algebra ODE-solvers in solving non-linear examples from Kamke's book is shown. | |||
| Date | April 1998 | |||
| Comments | Submitted to: Journal of Symbolic Computation | |||
| Report | Integrating Factors and ODE Patterns (PDF) | 
      Compressed
      PostScript: Integrating Factors and ODE Patterns (PS.Z)  | ||
| CS-98-06 | ||||
|---|---|---|---|---|
| Title | Shadow Volume Reconstruction | |||
| Authors | M.D. McCool | |||
| Abstract | 
      Current
      graphics
      hardware
      can
      be
      used
      to
      generate
      shadows
      using
      either
      shadow
      volumes
      or
      shadow
      maps.
      However,
      the
      shadow
      volume
      technique
      requires
      access
      to
      a
      represention
      of
      the
      scene
      as
      a
      polygonal
      model,
      and
      shadow
      maps
      currently
      require
      extensions
      to
      (and
      interfere
      with
      the
      use
      of)
      texture
      mapping. We present a hybrid of the shadow map and shadow volume approaches which does not have these difficulties. The scene is rendered from the point of view of the light source and a sampled depth map is recovered. Computer vision techniques are used to reconstruct a minimal shadow volume boundary, after which the shadows can be rendered using only a one bit stencil buffer.  | |||
| Comments | 
         This report was typeset in LaTeX, but has been converted to PostScript. It contains colour images, but can be printed on a high-resolution black and white laser printer with halftoning. This report has been submitted to the ACM Transactions on Graphics. There is a web site which contains more information on this and other rendering projects in CGL. The pages for this algorithm include slides from a talk and colour images.  | |||
| Report | No report | |||
| CS-98-05 | ||||
|---|---|---|---|---|
| Title | Discrete Parisian and Delayed Barrier Options: A General Numerical Approach | |||
| Authors | K.R. Vetzal and P.A. Forsyth | |||
| Abstract | In this paper we present a numerical method for the valuation of derivative securities which have a payoff dependent upon the amount of time during the life of the contract that some underlying variable lies within a specified range. We concentrate in particular on the examples of Parisian options and delayed barrier options, but our approach is easily adapted to other cases such as switch options and step options. Available analytic pricing formula are based on the assumption that the underlying variable is monitored continuously. In contrast, we consider discrete (e.g.\ daily or weekly) sampling. Given that path-dependent option values are known to be generally very sensitive to sampling frequency, this is an important advantage of our numerical approach. | |||
| Date | March 1998 | |||
| Report | Discrete Parisian and Delayed Barrier Options: A General Numerical Approach (PDF) | 
      Compressed
      PostScript: Discrete Parisian and Delayed Barrier Options: A General Numerical Approach (PS.Z)  | ||
| CS-98-04 | ||||
|---|---|---|---|---|
| Title | Lock-Free Distributed Objects: A Shared Spreadsheet | |||
| Authors | C.R. Palmer and G.V. Cormack | |||
| Abstract | A Lock-Free Distributed System is a purely-replicated environment (replication with no central authority) in which updates are performed with no inter-object communication. All replicated copies of an object take on a common state when there are no messages in transit. Such a system is often used for groupware applications and operation transformations are a popular technique in this field. We broaden the scope of operation transformations by using a lock-free concurrency system to specify a distributed spreadsheet. The resulting spreadsheet is highly fault tolerant and the interactive performance is independent of the speed and the quality of the underlying network. To specify the concurrent semantics of the spreadsheet, an abstract data type is defined and a general model of a subset of the operations is proposed. | |||
| Date | February 1998 | |||
| Report | Lock-Free Distributed Objects: A Shared Spreadsheet (PDF) | 
      Compressed
      PostScript: Lock-Free Distributed Objects: A Shared Spreadsheet (PS.Z)  | ||
| CS-98-03 | ||||
|---|---|---|---|---|
| Title | A Formalization of Shestakov's Decomposition | |||
| Authors | J.J. Lou and J.A. Brzozowski | |||
| Abstract | We consider two methods for the decomposition of Boolean and multi-valued functions into functions with fewer arguments. Shestakov's method (which we call double decomposition) expresses a function f(x_1,... ,x_n) as a composite function h(g_1(u_1,...,u_r),g(v_1,...,v_s)), where the union of U={u_1,...,u_r} and V={v_1,...,v_s} is the set X={x_1,...,x_n}. The independently developed method of Luba and Selvaraj (which we call single decomposition expresses a function f(x_1,...,x_n) as a composite function h(u_1,...,u_r,g(v_1,...,v_s)). The latter method has been formalized by Brzozowski and Luba using "blankets", which are generalizations of set systems. In this paper, we use the same blanket approach to formalize Shestakov's decomposition method. We compare the two methods, and verify that double decomposition is equivalent to two steps of single decomposition. Recently, Brzozowski and Lou extended the single decomposition methods to multi-valued functions. Using the same approach, we also extend Shestakov's method to the multi-valued case. | |||
| Date | February 1998 | |||
| Report | A Formalization of Shestakov's Decomposition (PDF) | 
      Compressed
      PostScript: A Formalization of Shestakov's Decomposition (PS.Z)  | ||
| CS-98-02 | ||||
|---|---|---|---|---|
| Title | Testing for Input Stuck-at Faults in Content-Addressable Memories | |||
| Authors | P.R. Sidorowicz and J.A. Brzozowski | |||
| Abstract | 
      Results
      pertaining
      to
      testing
      for
      input
      stuck-at
      faults
      in
      a
      n-word
      by
      l-bit
      static
      CMOS
      content-addressable
      memory
      (CAM)
      array
      are
      presented.
      First,
      a
      formal
      approach
      to
      modelling
      CAM
      cells
      is
      developed.
      The
      basis
      of
      this
      approach
      is
      the
      mathematical
      framework
      proposed
      by
      Brzozowski
      and
      Jurgensen
      for
      testing
      and
      diagnosis
      of
      sequential
      machines.
      Next,
      an
      input
      stuck-at
      fault
      model
      for
      a
      CAM
      is
      defined
      and
      a
      test
      of
      length
      7n+2l+5
      with
      100%
      fault
      coverage
      with
      respect
      to
      this
      fault
      model
      is
      constructed.
      This
      test
      also
      detects
      all
      the
      usual
      cell
      stuck-at
      and
      transition
      faults.
      Some
      design-for-testability
      (DFT)
      modifications
      facilitating
      a
      further
      reduction
      of
      this
      test's
      length
      are
      also
      proposed.
      Finally,
      two
      other
      CAM
      tests
      are
      verified
      with
      respect
      to
      our
      fault
      model. Keywords:CMOS, content-addressable, design for testability, fault modelling, stuck-at faults, testing.  | |||
| Date | April 1998 | |||
| Comments | This research was supported by the Natural Sciences and Engineering Research Council of Canada under grant No. OGP0000871. | |||
| Report | Testing for Input Stuck-at Faults in Content-Addressable Memories (PDF) | 
      Compressed
      PostScript: Testing for Input Stuck-at Faults in Content-Addressable Memories (PS.Z)  | ||