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Technical Reports Collection
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  1. Measuring the Size of Large No-Limit Poker Games [Download]

    Title: Measuring the Size of Large No-Limit Poker Games
    Creator: Johanson, Michael
    Description: In the field of computational game theory, games are often compared in terms of their size. This can be measured in several ways, including the number of unique game states, the number of decision points, and the total number of legal actions over all decision points. These numbers are either known or estimated for a wide range of classic games such as chess and checkers. In the stochastic and imperfect information game of poker, these sizes are easily computed in "limit" games which restrict the players' available actions, but until now had only been estimated for the more complicated "no-limit" variants. In this paper, we describe a simple algorithm for quickly computing the size of two-player no-limit poker games, provide an implementation of this algorithm, and present for the first time precise counts of the number of game states, information sets, actions and terminal nodes in the no-limit poker games played in the Annual Computer Poker Competition.
    Subjects: Artificial Intelligence, poker, game theory
    Date Created: Feb 26, 2013
  2. Support for Document Entry in a Multimedia Database [Download]

    Title: Support for Document Entry in a Multimedia Database
    Creator: El-Medani, Sherine
    Description: Technical report TR96-23. This Technical Report describes a document entry system that supports the automatic insertion of documents with arbitrary types into a multimedia database. The documents conform to the international standards of SGML and HyTime. This is achieved by instantiating objects in the database to represent the document components. These are persistent objects that can be queried and retrieved using a query interface. To achieve this goal, the database has to be queried dynamically to retrieve meta-information about the document structure. A generic meta type system was designed to model such meta-information. This type system consists of a number of built-in types that model the characteristics common to SGML document components. Whenever support for a new class of documents is added to the system, meta types modeling the characteristics specific to this class are dynamically generated and added to the meta type system. To insert documents conforming to this class into the database, two system components were developed: the SGML Parser and the Instance Generator. The SGML Parser validates the SGML documents to ensure database consistency. The Instance Generator instantiates the appropriate database objects to represent the document.
    Subjects: Multimedia databases, SGML Parser, Instance Generator, document entry system, dynamic querying
    Date Created: 1996
  3. A Generic Type System for an Object-Oriented Multimedia Database System [Download]

    Title: A Generic Type System for an Object-Oriented Multimedia Database System
    Creator: Schone, Manuela
    Description: Technical report TR96-14. This Technical Report is based upon an M.Sc. thesis in the Department of Computing Science at the University of Alberta. It describes the design of a generic multimedia database system that supports a wide class of documents. The design is characterized by an object-oriented approach and a strict adherence to the international standards SGML and HyTime. In order to support different multimedia applications, a multimedia type system must be flexible and extensible. This is achieved by defining a number of built-in types that model primitive multimedia objects, the spatial and temporal relationships between them, and characteristics that are common to all SGML documents and their components. Whenever support for a new class of documents is added to the multimedia database system, types modeling the characteristics specific to this class of documents are dynamically created and added to the type system. These types model the components and structure of the new document class.
    Subjects: Database Systems
    Date Created: 1996
  4. Characterization of Solutions to block triangular Hankel Systems [Download]

    Title: Characterization of Solutions to block triangular Hankel Systems
    Creator: Kossowski, P.
    Description: Technical report TR95-06. A full characterization of solutions is given for a certain class of under-determined triangular block Hankel systems of linear equations. Solutions of these systems correspond to Pade' approximants for bivariate power series with coefficients from a field.
    Subjects: bivariate Pade' aprroximants, block Hankel matrices
    Date Created: 1995
  5. Well-covered graphs: some new sub-classes and complexity results [Download]

    Title: Well-covered graphs: some new sub-classes and complexity results
    Creator: Sankaranarayana, Ramesh
    Description: Technical report TR94-02. A graph is said to be well covered if every maximal independent set has the same size, and very well covered if every maximal independent set contains exactly half the vertices in the graph. Well-covered graphs are of interest because while the problem of finding the size of a maximum independent set is NP-complete for graphs in general, it is in P for well-covered graphs. Many of the existing results in this area deal with characterizations of families of well-covered graphs. This thesis focuses on the algorithmic properties of this family. The first part of this thesis looks at the algorithmic complexities of the following problems for the families of well-covered and very well covered graphs: chromatic number, clique cover, clique partition, dominating cycle, dominating set, Hamiltonian cycle, Hamiltonian path, independent set, independent dominating set, maximum cut, minimum fill-in, recognition, Steiner tree, and vertex cover. While most of the above problems prove to be as difficult for well-covered graphs as for graphs in general, a number of them become tractable when restricted to the family of very well covered graphs. In the second part of this thesis, an alternative characterization is given for the family of well-covered graphs. This leads to the concept of a maximal intersection of independent sets. Based on this, a hierarchy of four new sub-classes of well-covered graphs is defined. The families are characterized and the algorithmic complexities of the above mentioned problems are studied for these families. It is also shown that the last class in the hierarchy is exactly the family of very well covered graphs without isolated vertices. A generalization of Favaron's theorem for very well covered graphs is also proved.
    Subjects: very well covered graphs, complexity results, Well-covered graphs, new sub-classes, characterization
    Date Created: 1994
  6. Mutable Object State for Object-Oriented Logic Programming: A Survey [Download]

    Title: Mutable Object State for Object-Oriented Logic Programming: A Survey
    Creator: Alexiev, Vladimir
    Description: Technical report TR93-15. One of the most difficult problems on the way to an integration of Object-Oriented and Logic Programming is the modeling of changeable object state(i.e. object dynamics) in a particular logic in order not to forfeit the declarative nature of LP. Classical logic is largely unsuitable for such a task, because it adopts a general (both temporally and spatially), Platonic notion of validity, whereas object state changes over time and is local to an object. This paper presents the problem and surveys the state-of-the-art approaches to its solution, as well as some emerging, promising new approaches. The paper tries to relate the different approaches, to evaluate their merits and deficiencies and to identify promising directions for development. The emphasis in this survey is on efficient implementation of state change, one which would be suitable for the lowest fundamental level of a general OOLP language. The following approaches are covered: Assert/Retract, Declarative Database Updates and Transaction Logic, Modal and Dynamic Logics, Perpetual Objects, Logical Objects and Linear Objects, Linear Logic, Rewriting Logic and MaudeLog.
    Subjects: Object-Oriented Logic Programming, survey, mutable object state
    Date Created: 1993
  7. Classifying Newgroup Questions on JTree and JButton [Download]

    Title: Classifying Newgroup Questions on JTree and JButton
    Creator: Hou, Daqing
    Description: Technical report TR05-07. In this study, we collected and analyzed 190 and 110 questions about JTree and JButton, respectively, from the Swing forum at forum.java.sun.com. We classified these questions by the design features of these two components. This classification leads to a better understanding why certain features are particularly difficult and the identification of problems with documentation.
    Subjects: Jtree, Jbutton, software development
    Date Created: 2005
  8. On the Comparison Cost of Partial Orders [Download]

    Title: On the Comparison Cost of Partial Orders
    Creator: Culberson, Joseph
    Description: Technical report TR88-01. A great deal of effort has been directed towards determining the minimum number of binary comparisons sufficient to produce various partial orders given some partial order. For example, the sorting problem considers the minimum number of comparisons sufficient to construct a total order starting from n elements. The merging problem considers the minimum number of comparisons sufficient to construct a total order from two total orders. The searching problem can be seen as a special case of the merging problem in which one of the total orders is a singleton. The selection problem considers the minimum number of comparisons sufficient to select the ith largest of n elements. Little, however, is known about the minimum number of comparisons sufficient to produce an arbitrary partial order. In this paper we briefly survey the known results on this problem and we present some first results on partial orders which can be produced using either restricted types of comparisons or a limited number of comparisons.
    Subjects: comparison based algorithms, lower bounds, poset, sorting, partial order
    Date Created: 1988
  9. Downward Path Preserving State Space Abstractions [Download]

    Title: Downward Path Preserving State Space Abstractions
    Creator: Zilles, Sandra
    Description: Technical report TR09-04. Abstraction is a popular technique for speeding up planning and search. A problem that often arises in using abstraction is the generation of abstract states, called spurious states, from which the goal state is reachable in the abstract space but for which there is no corresponding state in the original space from which the goal state can be reached. The experiments in this paper demonstrate that this problem may arise even when standard abstraction methodsare applied to benchmark planning problem domains: spurious states cause the pattern databases representing the heuristics to be excessively large and slow down planning and search by reducing the heuristic values. Known automated techniques to get rid of a large portion of spurious states turn out to avoid the memory problem, while at the same time not avoiding the problem of bad heuristic quality. The main contribution of this paper is theoretical. We formally define a characteristic property - the downward path preserving property (DPP) - that guarantees an abstraction will not contain spurious states. How this property can be achieved is studied both for techniques focussing on automated domain-independent abstraction and for techniques focussing on domain-specific abstraction. We analyze the computational complexity of (i) testing the downward path preserving property for a given state space and abstraction and of (ii) determining whether this property is achievable at all for a given state space. Strong hardness results show a close connection between these decision problems and the plan existence problem in typical planning settings including SAS+ and propositional STRIPS. On the positive side, we identify formal conditions under which finding downward path preserving abstractions is provably tractable and show that some popular heuristic search and planning domains have an encoding that matches these conditions. This includes a new encoding of the Blocks World domain, for which DPP abstractions can be easily defined.
    Subjects: downward path preserving property, abstraction, spurious states
    Date Created: 2009
  10. Using SIMD Registers and Instructions to Enable Instruction-Level Parallelism in Sorting Algorithms [Download]

    Title: Using SIMD Registers and Instructions to Enable Instruction-Level Parallelism in Sorting Algorithms
    Creator: Furtak, Timothy
    Description: Technical report TR07-02. Most contemporary processors offer some version of Single Instruction Multiple Data (SIMD) machinery -- vector registers and instructions to manipulate data stored in such registers. The central idea of this paper is to use these SIMD resources to improve the performance of the tail of recursive sorting algorithms. When a recursive computation reaches a set threshold, data is loaded into the vector registers, manipulated in-register, and the result stored back to memory. Four implementations of sorting with two different SIMD machinery -- x86-64's SSE2 and G5's AltiVec -- demonstrate that this idea delivers significant performance improvement. The improvements provided by the tail optimization of sorting are orthogonal to the gains obtained through empirical search for a suitable sorting algorithm. When integrated with the Dynamically Tuned Sorting Library (DTSL), this new code generation strategy improves the performance of DTSL by up to 18%. Performance of d-heaps is similarly improved by up to 35%.
    Subjects: Sorting networks, Vectorization, Sorting, Instruction-level parallelism, Quicksort, d-Heaps, SIMD, SSE
    Date Created: 2007