219,034 research outputs found
How Scale Affects Structure in Java Programs
Many internal software metrics and external quality attributes of Java
programs correlate strongly with program size. This knowledge has been used
pervasively in quantitative studies of software through practices such as
normalization on size metrics. This paper reports size-related super- and
sublinear effects that have not been known before. Findings obtained on a very
large collection of Java programs -- 30,911 projects hosted at Google Code as
of Summer 2011 -- unveils how certain characteristics of programs vary
disproportionately with program size, sometimes even non-monotonically. Many of
the specific parameters of nonlinear relations are reported. This result gives
further insights for the differences of "programming in the small" vs.
"programming in the large." The reported findings carry important consequences
for OO software metrics, and software research in general: metrics that have
been known to correlate with size can now be properly normalized so that all
the information that is left in them is size-independent.Comment: ACM Conference on Object-Oriented Programming, Systems, Languages and
Applications (OOPSLA), October 2015. (Preprint
Agile, Web Engineering and Capability Maturity ModelI ntegration : A systematic literature review
Context
Agile approaches are an alternative for organizations developing software, particularly for those who develop Web applications. Besides, CMMI (Capability Maturity Model Integration) models are well-established approaches focused on assessing the maturity of an organization that develops software. Web Engineering is the field of Software Engineering responsible for analyzing and studying the specific characteristics of the Web. The suitability of an Agile approach to help organizations reach a certain CMMI maturity level in Web environments will be very interesting, as they will be able to keep the ability to quickly react and adapt to changes as long as their development processes get mature.
Objective
This paper responds to whether it is feasible or not, for an organization developing Web systems, to achieve a certain maturity level of the CMMI-DEV model using Agile methods.
Method
The proposal is analyzed by means of a systematic literature review of the relevant approaches in the field, defining a characterization schema in order to compare them to introduce the current state-of-the-art.
Results
The results achieved after the systematic literature review are presented, analyzed and compared against the defined schema, extracting relevant conclusions for the different dimensions of the problem: compatibility, compliance, experience, maturity and Web.
Conclusion
It is concluded that although the definition of an Agile approach to meet the different CMMI maturity levels goals could be possible for an organization developing Web systems, there is still a lack of detailed studies and analysis on the field
Empirical modelling principles to support learning in a cultural context
Much research on pedagogy stresses the need for a broad perspective on learning. Such a perspective might take account (for instance) of the experience that informs knowledge and understanding [Tur91], the situation in which the learning activity takes place [Lav88], and the influence of multiple intelligences [Gar83]. Educational technology appears to hold great promise in this connection. Computer-related technologies such as new media, the internet, virtual reality and brain-mediated communication afford access to a range of learning resources that grows ever wider in its scope and supports ever more sophisticated interactions.
Whether educational technology is fulfilling its potential in broadening the horizons for learning activity is more controversial. Though some see the successful development of radically new educational resources as merely a matter of time, investment and engineering, there are also many critics of the trends in computer-based learning who see little evidence of the greater degree of human engagement to which new technologies aspire [Tal95].
This paper reviews the potential application to educational technology of principles and tools for computer-based modelling that have been developed under the auspices of the Empirical Modelling (EM) project at Warwick [EMweb]. This theme was first addressed at length in a previous paper [Bey97], and is here revisited in the light of new practical developments in EM both in respect of tools and of model-building that has been targetted at education at various levels. Our central thesis is that the problems of educational technology stem from the limitations of current conceptual frameworks and tool support for the essential cognitive model building activity, and that tackling these problems requires a radical shift in philosophical perspective on the nature and role of empirical knowledge that has significant practical implications.
The paper is in two main sections. The first discusses the limitations of the classical computer science perspective where educational technology to support situated learning is concerned, and relates the learning activities that are most closely associated with a cultural context to the empiricist perspective on learning introduced in [Bey97]. The second outlines the principles of EM and describes and illustrates features of its practical application that are particularly well-suited to learning in a cultural setting
Designing as Construction of Representations: A Dynamic Viewpoint in Cognitive Design Research
This article presents a cognitively oriented viewpoint on design. It focuses
on cognitive, dynamic aspects of real design, i.e., the actual cognitive
activity implemented by designers during their work on professional design
projects. Rather than conceiving de-signing as problem solving - Simon's
symbolic information processing (SIP) approach - or as a reflective practice or
some other form of situated activity - the situativity (SIT) approach - we
consider that, from a cognitive viewpoint, designing is most appropriately
characterised as a construction of representations. After a critical discussion
of the SIP and SIT approaches to design, we present our view-point. This
presentation concerns the evolving nature of representations regarding levels
of abstraction and degrees of precision, the function of external
representations, and specific qualities of representation in collective design.
Designing is described at three levels: the organisation of the activity, its
strategies, and its design-representation construction activities (different
ways to generate, trans-form, and evaluate representations). Even if we adopt a
"generic design" stance, we claim that design can take different forms
depending on the nature of the artefact, and we propose some candidates for
dimensions that allow a distinction to be made between these forms of design.
We discuss the potential specificity of HCI design, and the lack of cognitive
design research occupied with the quality of design. We close our discussion of
representational structures and activities by an outline of some directions
regarding their functional linkages
Sequential Monte Carlo pricing of American-style options under stochastic volatility models
We introduce a new method to price American-style options on underlying
investments governed by stochastic volatility (SV) models. The method does not
require the volatility process to be observed. Instead, it exploits the fact
that the optimal decision functions in the corresponding dynamic programming
problem can be expressed as functions of conditional distributions of
volatility, given observed data. By constructing statistics summarizing
information about these conditional distributions, one can obtain high quality
approximate solutions. Although the required conditional distributions are in
general intractable, they can be arbitrarily precisely approximated using
sequential Monte Carlo schemes. The drawback, as with many Monte Carlo schemes,
is potentially heavy computational demand. We present two variants of the
algorithm, one closely related to the well-known least-squares Monte Carlo
algorithm of Longstaff and Schwartz [The Review of Financial Studies 14 (2001)
113-147], and the other solving the same problem using a "brute force" gridding
approach. We estimate an illustrative SV model using Markov chain Monte Carlo
(MCMC) methods for three equities. We also demonstrate the use of our algorithm
by estimating the posterior distribution of the market price of volatility risk
for each of the three equities.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS286 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
An Exploratory Study of Forces and Frictions affecting Large-Scale Model-Driven Development
In this paper, we investigate model-driven engineering, reporting on an
exploratory case-study conducted at a large automotive company. The study
consisted of interviews with 20 engineers and managers working in different
roles. We found that, in the context of a large organization, contextual forces
dominate the cognitive issues of using model-driven technology. The four forces
we identified that are likely independent of the particular abstractions chosen
as the basis of software development are the need for diffing in software
product lines, the needs for problem-specific languages and types, the need for
live modeling in exploratory activities, and the need for point-to-point
traceability between artifacts. We also identified triggers of accidental
complexity, which we refer to as points of friction introduced by languages and
tools. Examples of the friction points identified are insufficient support for
model diffing, point-to-point traceability, and model changes at runtime.Comment: To appear in proceedings of MODELS 2012, LNCS Springe
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