7140389
Overcoming Ontology Mismatches in Transactions with Self-Describing Service Agents
One vision of the "Semantic Web" of the future is that software agents will interact with each other using formal metadata that reveal their interfaces. We examine one plausible paradigm, where agents provide service descriptions that tell how they can be used to accomplish other agents' goals. From the point of view of these other agents, the problem of deciphering a service description is quite similar to the standard AI planning problem, with some interesting twists. Two such twists are the possibility of having to reconcile contradictory ontologies -- or conceptual frameworks -- used by the agent, and having to rearrange the data structures of a message-sending agent so they match the expectations of the recipient. We argue that the former problem requires human intervention and maintenance, but that the latter can be fully automated.
7947888
Constructing Specification Morphisms
Specification morphisms underlie the refinement of algebraic specifications and provide the logical foundations for algorithm and data structure design. We present four techniques for formally, even mechanically, constructing specification morphisms. The first two techniques, verifying a manually constructed signature morphism and composition of specification morphisms are well-known. The remaining two techniques exploit the axioms of the source specification to help infer the translation of sort and function symbols from the source specification. The third, unskolemization, finds the translation of a function symbol by replacing occurrences of it in an axiom by an existentially quantified variable. A constructive proof of the translated axiom yields a witness to the existential that serves as the desired translation of the function symbol. The fourth technique, connections between specifications, allows the transfer of structure from one specification morphism to another. The unskolemization and connection techniques arose as abstractions from the algorithm design tactics implemented in the KIDS program transformation system (Smith (1990)). They suggest a more general approach to providing mechanized support for applying design knowledge expressed axiomatically.
206511487
Composition and refinement of behavioral specifications
This paper presents a mechanizable framework for specifying, developing, and reasoning about complex systems. The framework combines features from algebraic specifications, abstract state machines, and refinement calculus, all couched in a categorical setting. In particular, we show how to extend algebraic specifications to evolving specifications (especs) in such a way that composition and refinement operations extend to capture the dynamics of evolving, adaptive, and self-adaptive software development, while remaining efficiently computable. The framework is partially implemented in the Epoxi system.
5281675
Algorithm Theories and Design Tactics
Abstract Algorithm theories represent the structure common to a class of algorithms, such as divide-and-conquer or backtrack. An algorithm theory for a class A provides the basis for design tactics—specialized methods for designing A -algorithms from formal problem specifications. We illustrate this approach with recent work on the theory of global search algorithms and briefly mention several others. Several design tactics have been implemented in the kids / cypress system and have been used to semiautomatically derive many algorithms.
13516557
The Design of Divide and Conquer Algorithms
Abstract The structure common to a class of divide and conquer algorithms is represented by a program scheme. A theorem is presented which relates the functionality of a divide and conquer algorithm to its structure and the functionalities of its subalgorithms. Several strategies for designing divide and conquer algorithms arise from this theorem and they are used to formally derive algorithms for sorting a list of numbers, forming the cartesian product of two sets, and finding the convex hull of a set of planar points.
5110731
A Problem Reduction Approach to Program Synthesis
Program synthesis is the transformation of a specification of a user's problem into a computer program. A problem reduction approach to program synthesis is presented. During synthesis the user's problem is decomposed in a top-down manner into a hierarchy of subproblems. with directly solveable subproblems at the bottom. Solving these subproblems results in the bottom-up composition of a program whose structure reflects the subproblem hierarchy. The program is guaranteed to satisfy the specification and to terminate on all legal inputs. We illustrate this approach by presenting the knowledge needed to synthesize a class of divide and conquer algorithms and by deriving a Merge sort algorithm.
12947717
The evolving mSpace platform: leveraging the semantic web on the trail of the memex
Vannevar Bush proposed the memex as a means to support building knowledge in the way he says the human brain works: by association. Achieving this vision has been a core motivation for hypertext research. In this paper, we suggest first that Bush's memex reflects an interaction paradigm rather than system design. Second, we propose that Semantic Web promises to provide the mechanisms to enable these interaction requirements. Third, we propose the mSpace framework and architecture as a platform to deploy lightweight Semantic Web applications which foreground associative interaction. We propose this lightweight approach as a means to evaluate both interaction needs and the cost/benefits of using Semantic Web technologies to support them.
8267445
Explaining design plans
The paper describes a methodology for generating quality explanations from design plans. In selecting items of information for inclusion in an explanation, the methodology considers the rationales behind the strategic knowledge and object-level knowledge specified in a design plan. Rhetorical structure theory and discourse focus tracking are utilised to determine textual structure, and to maintain discourse coherence and cohesion. Using a simple system of user modelling, it is shown how the methodology flexibly includes consideration of a user's knowledge, thus resulting in more focused and convincing explanations. The methodology is used to investigate follow-up explanations, and the generation of explanations from plans which contain a misconception on the part of the designer.
18928754
An improved algorithm to determine lower bounds for the fixed spectrum frequency assignment problem
Frequencies have to be assigned to transmitters whenever a radio network is established or modified. This is ideally done is a way which minimises interference in the network. Lower bounds are necessary to establish the effectiveness of the heuristic algorithms used for this task and to assess the quality of the assignments obtained. 
 
In the fixed spectrum frequency assignment problem the available frequencies are known in advance. The constraints are often binary constraints, specifying the necessary frequency separation between given pairs of transmitters. There may be penalties (or weights) associated with the violation of each constraint; it is then either necessary to minimise the number of constraints violated or, increasingly often, to minimise the sum of the weights associated with violated constraints. 
 
A technique for generating lower bounds for these quantities is presented. This is an evolution of a technique which has recently appeared in the literature. It produces better quality bounds, is in general significantly faster and allows larger problems to be handled.
26954991
Optimally Reliable Graphs for Both Vertex and Edge Failures
218,462. Pink, F. June 9, 1923. Separating by gravity. -Apparatus for separating liquids of different densities such as oil and water comprises a vessel of horizontally elongated form in which, as the mixture flows therethrough, the lighter liquid rises and collects in a part of the vessel, which is provided with a discharge valve actuated by the rise or fall of the level of the heavier liquid. The mixture enters a tank 1, provided with baffles 4, by an inlet 3. The lighter liquid rises between the baffles and flows backward along the top to a collecting- compartment 19, while the heavier liquid is discharged through a rising pipe 25 . The discharge valve 14 for the lighter liquid may be operated by a float 9 which is raised to close the valve by the heavier liquid, but falls and opens the valve when surrounded by the lighter liquid. The float may be directly connected to the valve 14 or may operate a slide valve controlling the supply of pressure fluid to a piston 12 which operates the valve 14. Or the float may control an electric switch to energize a solenoid or actuate a motor for opening and closing the valve 14. Alternatively, the float may be omitted and the compartment 19 provided with electrodes between which a current passes when the electrodes are immersed in impure, water but not when they are immersed in oil; the circuit includes a solenoid or motor for actuating the valve. A relief valve 22 for the discharge of air or oil may be provided. Heating coils 24 may also be provided. The baffles 4 may be mounted on vertical or horizontal pivots, or one part of each baffle may be fixed while another is pivoted. Apparatus is described in which the baffles extend to the top of the tank, and pipes are provided to conduct the lighter liquid from the compartments so formed to the compartment 19. The apparatus may be built into a ship as a part thereof, or the double bottom of a ship may be adapted for use as a separating chamber.
30879884
Generation of lower bounds for minimum span frequency assignment
Minimum span frequency assignment problems require lower bounds for the span in order to assess the quality of individual assignments, and to effectively compare different meta-heuristic algorithms. The generation of good lower bounds requires the identification of critical subproblems. These subproblems are subgraphs of a constraint graph. Sometimes clique subgraphs lead to good lower bounds. However for some problems the clique must be modified in order to obtain the best possible bound. This can be time consuming, requires manual intervention and is dependent on the initial clique obtained and the specific problem. For practical use, a simple bounding technique is needed that can be universally applied to all problems without modification. Two algorithms based on meta-heuristics are presented that aim to find a subproblem that gives the best possible lower bound. This avoids the need for clique detection routines and manual intervention, and gives a robust and automatic method for generating lower bounds for all minimum span problems. These algorithms use mathematical programming formulations of the frequency assignment problem. Extensive testing on a wide range of problems shows that bounds from the new algorithms match those using previous techniques, and in some cases are significantly better.