In Search of Effectful Dependent Types

Real world programming languages crucially depend on the availability of computational effects to achieve programming convenience and expressive power as well as program efficiency. Logical frameworks rely on predicates, or dependent types, to express detailed logical properties about entities. According to the Curry-Howard correspondence, programming languages and logical frameworks should be very closely related. However, a language that has both good support for real programming and serious proving is still missing from the programming languages zoo. We believe this is due to a fundamental lack of understanding of how dependent types should interact with computational effects. In this thesis, we make a contribution towards such an understanding, with a focus on semantic methods.Comment: PhD thesis, Version submitted to Exam School

Memory support for desktop search

The user's memory plays a very important role in desktop search. A search query with insufficiently or inaccurately recalled information may make the search dramatically less effective. In this paper, we discuss three approaches to support user’s memory during desktop search. These include extended types of well remembered search options, the use of past search queries and results, and search from similar items. We will also introduce our search system which incorporates these features

Searches on star graphs and equivalent oracle problems

We examine a search on a graph among a number of different kinds of objects (vertices), one of which we want to find. In a standard graph search, all of the vertices are the same, except for one, the marked vertex, and that is the one we wish to find. We examine the case in which the unmarked vertices can be of different types, so the background against which the search is done is not uniform. We find that the search can still be successful, but the probability of success is lower than in the uniform background case, and that probability decreases with the number of types of unmarked vertices. We also show how the graph searches can be rephrased as equivalent oracle problems

The Invisible Web: A Quick Overview

This article provides a quick overview of recent literature published about the Invisible Web. In particular, this article covers such topics as what is the Invisible Web, weaknesses of popular search engines, types of information found on the Invisible Web, when to use the Invisible Web, search tools and search strategies

Theory-based user modeling for personalized interactive information retrieval

In an effort to improve users’ search experiences during their information seeking process, providing a personalized information retrieval system is proposed to be one of the effective approaches. To personalize the search systems requires a good understanding of the users. User modeling has been approved to be a good method for learning and representing users. Therefore many user modeling studies have been carried out and some user models have been developed. The majority of the user modeling studies applies inductive approach, and only small number of studies employs deductive approach. In this paper, an EISE (Extended Information goal, Search strategy and Evaluation threshold) user model is proposed, which uses the deductive approach based on psychology theories and an existing user model. Ten users’ interactive search log obtained from the real search engine is applied to validate the proposed user model. The preliminary validation results show that the EISE model can be applied to identify different types of users. The search preferences of the different user types can be applied to inform interactive search system design and development

Evaluating tag-based information access in image collections

The availability of social tags has greatly enhanced access to information. Tag clouds have emerged as a new "social" way to find and visualize information, providing both one-click access to information and a snapshot of the "aboutness" of a tagged collection. A range of research projects explored and compared different tag artifacts for information access ranging from regular tag clouds to tag hierarchies. At the same time, there is a lack of user studies that compare the effectiveness of different types of tag-based browsing interfaces from the users point of view. This paper contributes to the research on tag-based information access by presenting a controlled user study that compared three types of tag-based interfaces on two recognized types of search tasks - lookup and exploratory search. Our results demonstrate that tag-based browsing interfaces significantly outperform traditional search interfaces in both performance and user satisfaction. At the same time, the differences between the two types of tag-based browsing interfaces explored in our study are not as clear. Copyright 2012 ACM

In Search of Dental Care: Two Types of Dentist Shortages Limit Children's Access to Care

Each year in the United States, tens of millions of children, disproportionately low-income, go without seeing a dentist.This lack of access to dental care is a complex problem fueled by a number of factors, with two different dentist shortages compounding the issue: An uneven distribution of dentists nationwide means many areas do not have an adequate supply of these practitioners. As a result, access to care is constrained for people in these communities regardless of income or insurance coverage.The relatively small number of dentists who participate in Medicaid means that many low-income people are not receiving dental care.National standards set by dental and pediatric organizations call for children to visit a dentist every six months.The federal government requires state Medicaid programs to enact their own standards after consulting with these organizations, but new data show that more than 14 million children enrolled in Medicaid did not receive any dental service in 2011.According to the most recent comparison, in 2010, privately insured children were almost 30 percent more likely to receive dental care than those who were publicly insured through Medicaid or other government programs, even though low-income children are almost twice as likely as their wealthier peers to develop cavities.4 In 22 states, fewer than half of Medicaid-enrolled children received dental care in 2011.In 2012, Dr. Louis W. Sullivan, secretary of health and human services under President George H.W. Bush, said, "In a nation obsessed with high-tech medicine, people are not getting preventive care for something as simple as tooth decay." He pointed to the inadequate dental workforce as a driving factor, stating, "The shortage of dental care is going to get only worse."This issue brief examines the lack of access to dental care, especially for low-income children and families, in the United States. It also explores strategies states are employing -- particularly expansion of the dental team by licensing additional types of providers -- to address workforce shortages and better serve low-income children

Session Type Isomorphisms

There has been a considerable amount of work on retrieving functions in function libraries using their type as search key. The availability of rich component specifications, in the form of behavioral types, enables similar queries where one can search a component library using the behavioral type of a component as the search key. Just like for function libraries, however, component libraries will contain components whose type differs from the searched one in the order of messages or in the position of the branching points. Thus, it makes sense to also look for those components whose type is different from, but isomorphic to, the searched one. In this article we give semantic and axiomatic characterizations of isomorphic session types. The theory of session type isomorphisms turns out to be subtle. In part this is due to the fact that it relies on a non-standard notion of equivalence between processes. In addition, we do not know whether the axiomatization is complete. It is known that the isomorphisms for arrow, product and sum types are not finitely axiomatisable, but it is not clear yet whether this negative results holds also for the family of types we consider in this work.Comment: In Proceedings PLACES 2014, arXiv:1406.331

Using tabu search and genetic algorithms in mathematics research

This paper discusses an ongoing project which uses computational heuristic search techniques such as tabu search and genetic algorithms as a tool for mathematics research. We discuss three ways in which such search techniques can be useful for mathematicians: in nding counterexamples to conjectures, in enumerating examples, and in nding sequences of transformations between two objects which are conjectured to be related. These problem-types are discussed using examples from topology