16901228
Planware-domain-specific synthesis of high-performance schedulers
Planware is a domain-specific generator of high-performance scheduling software, currently being developed at the Kestrel Institute. Architecturally, Planware is an extension of the Specware system with domain-independent and domain-dependent parts. The domain-independent part includes a general algorithm design facility (including mechanisms to synthesize global-search and constraint propagation algorithms), as well as support for theorem-proving and witness finding. The domain-dependent part includes scheduling domain knowledge and architecture representations, and other domain-specific refinement knowledge that relates the scheduling domain to general algorithm design and data type refinement. Using Planware, the user interactively specifies a problem and then the system automatically generates a formal specification and refines it.
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.
17878068
Guarded Transitions in Evolving Specifications
We represent state machines in the category of specifications, where assignment statements correspond exactly to interpretations between theories [7, 8]. However, the guards on an assignment require a special construction. In this paper we raise guards to the same level as assignments by treating each as a distinct category over a shared set of objects. A guarded assignment is represented as a pair of arrows, a guard arrow and an assignment arrow. We give a general construction for combining arrows over a factorization system, and show its specialization to the category of specifications. This construction allows us to define the fine structure of state machine morphisms with respect to guards. Guards define the flow of control in a computation, and how they may be translated under refinement is central to the formal treatment of safety, liveness, concurrency, and determinism.
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.
12681881
Synthesis of Constraint 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.
45395534
A Study of Permutation Crossover Operators on the Traveling Salesman Problem
15706733
Integrating harvesting into digital library content
The Open Archives Initiative has gained success by aiming between complex federation schemes and low functionality web crawling. Much information still remains hidden inside documents catalogued by OAI metadata. We discuss how subdocument information can be exposed by data providers and exploited by service providers. We discuss services for citation reversal and name and term linking with harvested data in the Perseus Project's document management system and a proxy service for automatically adding these links to OAI documents outside Perseus.
17019446
A two-echelon inventory model with lost sales
Abstract This paper considers a single-item, two-echelon, continuous-review inventory model. A number of retailers have their stock replenished from a central warehouse. The warehouse in turn replenishes stock from an external supplier. The demand processes on the retailers are independent Poisson. Demand not met at a retailer is lost. The order quantity from each retailer on the warehouse and from the warehouse on the supplier takes the same fixed value Q , an exogenous variable determined by packaging and handling constraints. Retailer i follows a ( Q ,  R i ) control policy. The warehouse operates an ( SQ , ( S  − 1) Q ) policy, with non-negative integer S . If the warehouse is in stock then the lead time for retailer i is the fixed transportation time L i from the warehouse to that retailer. Otherwise retailer orders are met, after a delay, on a first-come first-served basis. The lead time on a warehouse order is fixed. Two further assumptions are made: that each retailer may only have one order outstanding at any time and that the transportation time from the warehouse to a retailer is not less than the warehouse lead time. The performance measures of interest are the average total stock in the system and the fraction of demand met in the retailers. Procedures for determining these performance measures and optimising the behaviour of the system are developed.
7569023
Journey planning based on user needs
In this paper we discuss potential developments to the design of pre-trip in-home journey planning services, to include support for additional user needs. These needs were identified through stakeholder interviews as contributing to actual decisions in route selection scenarios and include: safety, weather and even fitness. A journey planner was designed to allow users to articulate these constraints and a series of paper prototypes were evaluated through cognitive walkthroughs. An exploratory study compared three designs and provided rationale for the most effective interaction method, informing an implementation plan.
13000609
Disambiguating Geographic Names in a Historical Digital Library
Geographic interfaces provide natural, scalable visualizationss for many digital library collections, but the wide range of data in digital libraries presents some particular problems for identifying and disambiguating place names. We describe the toponym-disambiguation system in the Perseus digital library and evaluate its performance. Name categorization varies significantly among different types of documents, but toponym disambiguation performs at a high level of precision and recall with a gazetteer an order of magnitude larger than most other applications.