44 research outputs found
Effectiveness, Productivity and Satisfaction of Persons with Sight and Motor Disabilities when using Dynamic Text-only Pages
No full textText transcoders are web–server systems that produce, on the fly, a text–only version
of a web page requested by a user of a browser. Although the potential benefits of text
transcoders are multifaceted and discussions on appropriateness of text transcoders to
produce accessible versions of web sites are still ongoing, at the moment the impact of
transcoded pages on disabled web users has not yet been scientifically studied.
This paper describes an experiment aimed at evaluating usability of web pages pro-
cessed by a text transcoder and used by 29 disabled persons. Results based on subjective
and objective data show how usability changes, and which results can be generalized to
a broader population
Generalized Coiteration Schemata
No full textCoiterative functions can be explained categorically as final coalgebraic morphisms, once coinductive types are viewed as final coalgebras. However, the coiteration schema which arises in this way is too rigid to accommodate directly many interesting classes of circular specifications. In this paper, building on the notion of T-coiteration introduced by the third author and capitalizing on recent work on bialgebras by Turi-Plotkin and Bartels, we introduce and illustrate various generalized coiteration patterns. First we show that, by choosing the appropriate monad T, T-coiteration captures naturally a wide range of coiteration schemata, such as the duals of primitive recursion and course-of-value iteration, and mutual coiteration. Then we show that, in the more structured categorical setting of bialgebras, T-coiteration captures guarded coiterations schemata, i.e. specifications where recursive calls appear guarded by predefined algebraic operations
Some Properties and Some Problems on Set Functors
No full textWe study properties of functors on categories of sets (classes) together with set (class) functions. In particular, we investigate the notion of inclusion preserving functor, and we discuss various monotonicity and continuity properties of set functors. As a consequence of these properties, we show that some classes of set operators do not admit functorial extensions. Then, starting from Aczel's Special Final Coalgebra Theorem, we study the class of functors uniform on maps, we present and discuss various examples of functors which are not uniform on maps but still inclusion preserving, and we discuss simple characterization theorems of final coalgebras as fixpoints. We present a number of conjectures and problems
Functors Determined by Values on Objects
No full textFunctors which are determined, up to natural isomorphism, by their values on objects, are called DVO (Defined by Values on Objects). We focus on the collection of polynomial functors on a category of sets (classes), and we give a characterization theorem of the DVO functors over such collection of functors. Moreover, we show that the (κ-bounded) powerset functor is not DVO
Do dynamic text-only web pages improve usability for PDA users?
No full textText transcoders are proxy–like systems that respond to
requests sent by user’s browsers, strip images, multimedia
objects, JavaScript code and change the page layout. Al-
though the potential benefits of text transcoders as mecha-
nisms to provide alternative and robust user interfaces are
multifaceted, at the moment their benefits on users of small
mobile devices are not clear.
This paper describes an experiment aimed at evaluating us-
ability of web pages used with PDAs when processed by a
text transcoder. Results based on subjective and objective
data show that effectiveness, productivity and satisfaction
can be improved. Furthermore, the needed transformations
are simple to implement, and mostly achievable by many
text transcoders
Do text transcoders improve usability for disabled users?
No full textText transcoders are web--server systems that produce, on the fly, a text-only version of a web page requested by a user of a browser. Although the potential benefits of text transcoders axe multifaceted and discussions on appropriateness of text transcoders to produce accessible versions of web sites are still ongoing, at the moment the impact of transcoded pages on disabled web users has not been scientifically studied yet.This paper describes an experiment aimed at evaluating usability of web pages processed by a text transcoder and used by 29 disabled persons. Results based on subjective and objective data show how usability changes, and which results can be generalized to a wider population
Properties of Set Functors
No full textWe prove that any endofunctor on a class-theoretic category has a final coalgebra. Moreover, we characterize functors on set-theoretic categories which are identical on objects, and functors which are constant on objects
Phonological attrition and the perception of geminate consonants in the Lucchese community of San Francisco (CA)
No full textTwo perceptual tests, designed to investigate the discrimination of the singleton/geminate consonant contrast, were submitted to bilingual English-Lucchese immigrants in the USA, and monolingual Lucchese subjects. The study has two major goals. The first goal is to add a much-needed empirical contribution to the incredibly sparse literature on phonological/phonetic attrition in bilinguals. The second goal is to cast the analysis of phonological attrition for socio-linguistic reasons on a more general psycholinguistic framework for cross-language speech perception. As will be shown, the comparison between the performances of different groups of speakers in different perceptual tasks allowed us to verify that phonological attrition moves along patterns of perceptual sensitivity which can be fruitfully compared with those surfacing in L1/L2 phonological acquisition. © 2010 the Author
An industrial case study using an MBE approach: from architecture to safety analysis.
No full textWe discuss the initial phases of software development of a real industrial safety-related device in the railway application domain. In particular, to achieve greater confidence in the system, we illustrate the development of the system architecture (using a standard model domain-specific language), the computation of the safety integrity level and the calculation of the reliability of the whole system. We reiterate the safety analysis on the sub-systems. The proposed methodology has found immediate industrial applications
