17757718
Composition by Colimit and Formal Software Development
Goguen emphasized long ago that colimits are how to compose systems [7]. This paper corroborates and elaborates Goguen’s vision by presenting a variety of situations in which colimits can be mechanically applied to support software development by refinement. We illustrate the use of colimits to support automated datatype refinement, algorithm design, aspect weaving, and security policy enforcement.
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.
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.
12681881
Synthesis of Constraint Algorithms
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.
44957593
Toward a Classification Approach to Design
This paper addresses the problem of how to construct refinements of specifications formally and incrementally. The key idea is to use a taxonomy of abstract design concepts, each represented by a design theory An abstract design concept is applied by constructing a specification morphism from its design theory to a requirement specification. Procedures for propagating constraints, computing colimits, and constructing specification morphisms provide computational support for this approach. Although we conjecture that classification generally applies to the incremental application of knowledge represented in a taxonomy of design theories, this paper mainly focuses on algorithm design theories and presents several examples of design by classification.
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.
2029665
Minimum Risk Annealing for Training Log-Linear Models
When training the parameters for a natural language system, one would prefer to minimize 1-best loss (error) on an evaluation set. Since the error surface for many natural language problems is piecewise constant and riddled with local minima, many systems instead optimize log-likelihood, which is conveniently differentiable and convex. We propose training instead to minimize the expected loss, or risk. We define this expectation using a probability distribution over hypotheses that we gradually sharpen (anneal) to focus on the 1-best hypothesis. Besides the linear loss functions used in previous work, we also describe techniques for optimizing nonlinear functions such as precision or the BLEU metric. We present experiments training log-linear combinations of models for dependency parsing and for machine translation. In machine translation, annealed minimum risk training achieves significant improvements in BLEU over standard minimum error training. We also show improvements in labeled dependency parsing.
6938855
mSpace: improving information access to multimedia domains with multimodal exploratory search
Overview of mSpace interaction approach for presenting exploratory search particularly in the audio domain by using slices, preview cues, and user-determined organization of information from high-dimensional spaces
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.
1180538
mSpace mobile: a UI gestalt to support on-the-go info-interaction
mSpace Mobile Interaction presents a UI gestalt of 7 techniques for mobile/on-the-move information retrieval and assessment that enables multiple views of the information within a persistent focus+context viewer. It uses the web but breaks the web page paradigm to support effective rapid triage.