waashk/acm huggingface dataset:
join processing in relational databases  the join operation is one of the fundamental relational database query operations. it facilitates the retrieval of information from two different relations based on a cartesian product of the two relations. the join is one of the most diffidult operations to implement efficiently, as no predefined links between relations are required to exist (as they are with network and hierarchical systems). the join is the only relational algebra operation that allows the combining of related tuples from relations on different attribute schemes. since it is executed frequently and is expensive, much research effort has been applied to the optimization of join processing. in this paper, the different kinds of joins and the various implementation techniques are surveyed. these different methods are classified based on how they partition tuples from different relations. some require that all tuples from one be compared to all tuples from another; other algorithms only compare some tuples from each. in addition, some techniques perform an explicit partitioning, whereas others are implicit.  priti mishra margaret h. eich
an algorithm for inferring multivalued dependencies with an application to propositional logic  an algorithm is given for deciding whether a functional or a multivalued dependency  (with a right-hand side y) is implied by a set of functional and multivalued dependencies . the running time of the algorithm is o(| y |&amp;verbar; &amp;verbar;), where y is the number of attributes in y and &amp;verbar; &amp;verbar; is the size of the description of . the problem of constructing the dependency basis of a set of attributes x is also investigated. it is shown that the dependency basis can be found in o(s&amp;verbar; &amp;verbar;) time, where s is the number of sets in the dependency basis. since functional and multivalued dependencies correspond to a subclass of propositional logic (that can be viewed as a generalization of horn clauses), the algorithm given is also an efficient inference procedure for this subclass of propositional logic.  yehoshua sagiv
interface and data architecture for query preview in networked information systems  there are numerous problems associated with formulating queries on networked information systems. these include increased data volume and complexity, accompanied by slow network access. this article proposes a new approach to a network query user interfaces that consists of two phases: query preview and query refinement. this new approach is based on the concepts of dynamic queries and query previews, which guides users in rapidly and dynamically eliminating undesired records, reducing the data volume to a manageable size, and refining queries locally before submission over a network. examples of two applications are given: a restaurant finder and a prototype for nasa's earth observing systems data information systems (eosdis). data architecture is discussed, and user feedback is presented.  catherine plaisant ben shneiderman khoa doan tom bruns
formal process ontology the paper reports some results of the author's recent work on aprocess-ontological framework called apt. apt is based on thenotion of a free process, a new category in ontology, with broad's/ sellars' "subjectless" or "pure" processes as their closestcognates. with a pointer to verbal and nominal aspect shift asbackground motivation i argue that basic classificatory terms ofcommon sense reasoning (activity, event, thing, stuff, propertyetc.) can be treated as different types of free processes. afterintroducing essential elements of the formal framework of apt (anon- standard extensional mereology with a non-transitivepart-relation) i sketch apt-classifications of basic and complexprocesses, based on five main descriptive parameters: homomeritypattern, participant structure, dynamic composition, dynamic shape,and dynamic context. johanna seibt
answering queries with useful bindings in information-integration systems, sources may have diverse and limited query capabilities. to obtain maximum information from these restrictive sources to answer a query, one can access sources that are not specified in the query (i.e., off-query sources). in this article, we propose a query-planning framework to answer queries in the presence of limited access patterns. in the framework, a query and source descriptions are translated to a recursive datalog program. we then solve optimization problems in this framework, including how to decide whether accessing off-query sources is necessary, how to choose useful sources for a query, and how to test query containment. we develop algorithms to solve these problems, and thus construct an efficient program to answer a query. chen li edward chang
mlr: a recovery method for multi-level systems  to achieve high concurrency in a database system has meant building a system that copes well with important special cases. recent work on multi-level systems suggest a systematic path to high concurrency. a multi-level system using locks permits restrictive low level locks of a subtransaction to be replaced with less restrictive high level locks when sub-transactions commit, enhancing concurrency. this is possible because sub-transactions can be undone via high level compensation actions rather than by restoring a prior lower level state. we describe a recovery scheme, called multi-level recovery (mlr) that logs this high level undo operation with the commit record for the subtransaction that it compensates, posting log records to only a single log. a variant of the method copes with nested transactions, and both nested and multi-level transactions can be treated in a unified fashion.  david b. lomet
relevance and contributing information types of searched documents in task performance  end-users base the relevance judgements of the searched documents on the expected contribution to their task of the information contained in the documents. there is a shortage of studies analyzing the relationships between the experienced contribution, relevance assessments and type of information initially sought. this study categorizes the types of information in documents being used in writing a research proposal for a master's thesis by eleven students throughout the various stages of the proposal writing process. the role of the specificity of the searched information in influencing its contribution is analyzed. the results demonstrate that different types of information are sought at different stages of the writing process and thus the contribution of the information also differs at the different stages. the categories of the contributing information can be understood of topicality.  pertti vakkari
windowing vs scrolling on a visual display terminal  to study a different star the astronomer moves his telescope. to study a different bacterium the biologist moves his microscope slide. in the case of the astronomer, it is the viewing instrument that is being moved, while in the case of the biologist it is the viewed object that is being moved. these scientists have no choice, the nature of their equipment requires that they operate in a pre-defined way. the user of a video display terminal (vdt), however, can be given a choice. the vdt user views a representation of an area of computer memory. in most cases the portion of memory the user wishes to examine is much larger than that which will fit on the screen at one time. for this reason almost all vdt's are equipped with some sort of "scroll function" that allows the user to display data that is located beyond the limits of the screen.  kevin f. bury james m. boyle r. james evey alan s. neal
a review and taxonomy of distortion-oriented presentation techniques  one of the common problems associated with large computer-based information systems is the relatively small window through which an information space can be viewed. increasing interest in recent years has been focused on the development of distortion-oriented presentation techniques to address this problem. however, the growing number of new terminologies and techniques developed have caused considerable confusion to the graphical user interface designer, consequently making the comparison of these presentation techniques and generalization of empirical results of experiments with them very difficult, if not impossible. this article provides a taxonomy of distortion- oriented techniques which demonstrates clearly their underlying relationships. a unified theory is presented to reveal their roots and origins. issues relating to the implementation and performance of these techniques are also discussed.  y. k. leung m. d. apperley
xtract: a system for extracting document type descriptors from xml documents  xml is rapidly emerging as the new standard for data representation and exchange on the web. an xml document can be accompanied by a _document type descriptor_ (dtd) which plays the role of a schema for an xml data collection. dtds contain valuable information on the structure of documents and thus have a crucial role in the efficient storage of xml data, as well as the effective formulation and optimization of xml queries. in this paper, we propose xtract, a novel system for inferring a dtd schema for a database of xml documents. since the dtd syntax incorporates the full expressive power of _regular expressions_, naive approaches typically fail to produce concise and intuitive dtds. instead, the xtract inference algorithms employ a sequence of sophisticated steps that involve: (1) finding patterns in the input sequences and replacing them with regular expressions to generate "general" candidate dtds, (2) factoring candidate dtds using adaptations of algorithms from the logic optimization literature, and (3) applying the minimum description length (mdl) principle to find the best dtd among the candidates. the results of our experiments with real-life and synthetic dtds demonstrate the effectiveness of xtract's approach in inferring concise and semantically meaningful dtd schemas for xml databases.  minos garofalakis aristides gionis rajeev rastogi s. seshadri kyuseok shim
the character, value, and management of personal paper archives  we explored general issues concerning personal information management by investigating the characteristics of office workers' paper-based information, in an industrial research environment. we examined the reasons people collect paper, types of data they collect, problems encountered in handling paper, and strategies used for processing it. we tested three specific hypotheses in the course of an office move. the greater availability of public digital data along with changes in people's jobs or interests should lead to wholescale discarding of paper data, while preparing for the move. instead we found workers kept large, highly valued papar archives. we also expected that the major part of people's personal archives would be unique documents. however, only 49% of people's archives were unique documents, the remainder being copies of publicly available data and unread information, and we explore reasons for this. we examined the effects of paper-processing strategies on archive structure. we discovered different paper-processing strategies (filing and piling)that were relatively independent of job type. we predicated that filers' attempted to evaluate and catergorize incoming documents would produce smaller archives that were accessed frequently. contrary to our predictions, filers amassed more information, and accessed it less frequently than pilers. we argue that filers may engage in premature filing: to clear their workspace, they archives information that later turns out to be of low value. given the effort involved in organzing data, they are also loath to discard filed information, even when its value is uncertain. we discuss the implications of this research for digital personal information management.  steve whittaker julia hirschberg
experiences with hyperbase: a hypertext database supporting collaborative work  this paper describes the architecture and experiences with a hyperbase (hypertext database). hyperbase is based on the client-server model and has been designed especially to support collaboration. hyperbase has been used in a number of (hypertext) applications in our lab and is currently being used in research projects around the world to provide database support to all kinds of applications. one application from our lab is a multiuser hypertext system for collaboration which deals with three fundamental issues in simultaneous sharing: access contention, real-time monitoring and real-time communication. major experiences with hyperbase (collaboration support, data modeling and performance) gained from use both in our lab and in different projects at other research sites are reported. one major lesson learned is that hyperbase can provide powerful support for data sharing among multiple users simultaneously sharing the same environment.  uffe kock wiil
an empirical study of human web assistants: implications for user support in web information systems  user support is an important element in reaching the goal of universal usability for web information systems. recent developments indicate that human involvement in user support is a step towards this goal. however, most such efforts are currently being pursued on a purely intuitive basis. this, empirical findings about the role of human assistants are important. in this paper we present the findings from a field study of a general user support model for web information systems. we show that integrating human assistance into web systems is a way to provide efficient user support. further, this integration makes a web site more fun to use and increases the user's trust in the site. the support also improves the site atmosphere. our findings are summarised as recommendations and design guidelines for decision-makers and developers web systems.  johan aberg nahid shahmehri
performance analysis of file replication schemes in distributed systems  in distributed systems the efficiency of the network file system is a key performance issue. replication of files and directories can enhance file system efficiency, but the choice of replication techniques is crucial. this paper studies a number of replication techniques, including remote access, prereplication, weighted voting, and two demand replication schemes: polling and staling. it develops a markov chain model, which is capable of characterizing properties of file access sequences, including access locality and access bias. the paper compares the replication techniques under three different network file system architectures. the results show that, under reasonable assumptions, demand replication requires fewer file transfers than remote access, especially for files that have a high degree of access locality. among the demand replication schemes, staling requires fewer auxiliary messages than polling.  zuwang ruan walter f. tichy
hierarchical materialisation of methods in object-oriented views: design, maintenance, and experimental evaluation the application of materialised object-oriented views in object-relational data warehousing systems is promising. in this paper we propose a novel technique for the materialisation of method results in object-oriented views, called _hierarchical materialisation_. when an object used to materialise the result of method _m_ is updated, then _m_ has to be recomputed. this recomputation can use unaffected intermediate materialised results of methods called from _m_, thus reducing a recomputation time. the hierarchical materialisation technique was implemented and evaluated by a number of experiments concerning methods without input arguments as well as methods with input arguments. the results showed that hierarchical materialisation reduces method recomputation time. moreover, materialising methods with input arguments of narrow discrete domains introduces only a small time overhead. bartosz bebel robert wrembel
from usability lab to "design collaboratorium": reframing usability practice  this paper presents an exploratory process in which three industrial usability groups, in cooperation with hci researchers, worked to reframe their own work practice. the usability groups moved beyond a classical usability setting towards a new way of working which we have coined the design collaboratorium. this design collaboratorium is a design approach that creates an open physical and organizational space where design?, engineers, users and usability professionals meet and work alongside each other. at the same time the design collaboratorium makes use of event-driven ways of working known from participatory design. some of these working methods are well-documented from literature but adapted to the needs of the particular project, others are new. this paper illustrates how it is pos?le to reframe usability work and it discusses the new usability competence required.  jacob buur susanne bødker
deriving initial data warehouse structures from the conceptual data models of the underlying operational information systems  in recent years the construction of large scale data schemes for operational systems has been the major problem of conceptual data modeling for business needs. multidimensional data structures used for decision support applications in data warehouses have rather different requirements to data modeling techniques. in case of operational systems the data models are created from application specific requirements. the data models in data warehouses base on the analytical requirements of the users. furthermore, the development of data warehouse structures implicates the consideration of user-defined information requirements as well as the underlying operational source systems. in this paper we show that the conceptual data models of the underlying operational information systems can support the construction of multidimensional structures. we would like to point out that the special features of the structured entity relationship model (serm) are not only useful for the development of big operational systems but can also help with the derivation of data warehouse structures. the serm is an extension of the conventional entity relationship model (erm) and the conceptual basis of the data modeling technique used by the sap corporation. to illustrate the usefulness of this approach we explain the derivation of the warehouse structures from the conceptual data model of a flight reservation system.  michael boehnlein achim ulbrich-vom ende
frame-sliced partitioned parallel signature files  the retrieval capabilities of the signature file access method have become very attractive for many data processing applications dealing with both formatted and unformatted data. however, performance is still a problem, mainly when large files are used and fast response required. in this paper, a high performance signature file organization is proposed, integrating the latest developments both in storage structure and parallel computing architectures. it combines horizontal and vertical approaches to the signature file fragmentation. in this way, a new, mixed decomposition scheme, particularly suitable for parallel implementation, is achieved. the organization, based on this fragmentation scheme, is called fragmented signature file. performance analysis shows that this organization provides very good and relatively stable performance, covering the full range of possible queries. for the same degree of parallelism, it outperforms any other parallel signature file organization that has been defined so far. the proposed method also has other important advantages concerning processing of dynamic files, adaptability to the number of available processors, load balancing, and, to some extent, fault-tolerant query processing.  fabio grandi paolo tiberio pavel zezula
an incremental access method for viewcache: concept, algorithms, and cost analysis  a viewcache is a stored collection of pointers pointing to records of underlying relations needed to materialize a view. this paper presents an incremental access method (iam) that amortizes the maintenance cost of viewcaches over a long time period or indefinitely. amortization is based on deferred and other update propagation strategies. a deferred update strategy allows a viewcache to remain outdated until a query needs to selectively or exhaustively materialize the view. at that point, an incremental update of the viewcache is performed. this paper defines a set of conditions under which incremental access to the viewcache is cost effective. the decision criteria are based on some dynamically maintained cost parameters, which provide accurate information but require inexpensive bookkeeping.  the iam capitalizes on the viewcache storage organization for performing the update and the materialization of the viewcaches in an interleaved mode using one-pass algorithms. compared to the standard technique for supporting views that requires reexecution of the definition of the view, the iam offers significant performance advantages. we will show that under favorable conditions, most of which depend on the size of the incremental update logs between consecutive accesses of the views, the incremental access method outperforms query modification. performance gains are higher for multilevel viewcaches because all the i/o and cpu for handling intermediate results are avoided.  nicholas roussopoulos
towards usability guidelines for multimedia systems  the advent of technology which supports the concurrent presentation of information through a range of different media has raised new issues relating to the design of usable systems. while previous work in the areas of both human-computer interaction (hci) and hypermedia system usability can contribute a considerable amount to the development of such guidelines, we believe that the use of multiple output media demands an understanding of particular characteristics and limitations of users' attentional capabilities. this paper presents some initial guidelines for the design of usable multimedia systems. these guidelines are based on empirical findings regarding the nature of human attention derived from the field of experimental psychology. we believe that the provision of such guidelines for multimedia interface design will support designers in achieving the dual goals of maximising a user's flexibility in controlling the presentation of multiple concurrent media, while keeping cognitive load to an acceptable level.  m. bearne s. jones j. sapsford-francis