waashk/acm huggingface dataset:
on the design of relational database schemata  the purpose of this paper is to present a new approach to the conceptual design of relational databases based on the complete relatability conditions (crcs).  it is shown that current database design methodology based upon the elimination of anomalies is not adequate. in contradistinction, the crcs are shown to provide a powerful criticism for decomposition. a decomposition algorithm is presented which (1) permits decomposition of complex relations into simple, well-defined primitives, (2) preserves all the original information, and (3) minimizes redundancy.  the paper gives a complete derivation of the crcs, beginning with a unified treatment of functional and multivalued dependencies, and introduces the concept of elementary functional dependencies and multiple elementary multivalued dependencies. admissibility of covers and validation of results are also discussed, and it is shown how these concepts may be used to improve the design of 3nf schemata. finally, a convenient graphical representation is proposed, and several examples are described in detail to illustrate the method.  carlo zaniolo miachel a. meklanoff
lag as a determinant of human performance in interactive systems  the sources of lag (the delay between input action and output response) and its effects on human performance are discussed. we measured the effects in a study of target acquisition using the classic fitts' law paradigm with the addition of four lag conditions. at the highest lag tested (225 ms), movement times and error rates increased by 64% and 214% respectively, compared to the zero lag condition. we propose a model according to which lag should have a multiplicative effect on fitts' index of difficulty. the model accounts for 94% of the variance and is better than alternative models which propose only an additive effect for lag. the implications for the design of virtual reality systems are discussed.  i. scott mackenzie colin ware
user-oriented smart-cache for the web: what you seek is what you get!  standard database approaches to querying information on the web focus on the source(s) and provide a query language based on a given predefined organization (schema) of the data: this is the source- driven approach. however, can the web be seen as a standard database? there is no super-user in charge of monitoring the source(s) (the data is constantly updated), there is no homogeneous structure (no common explicit structure thus), the web itself never stops growing, etc. for these reasons, we believe that the source-driven standard approach is not suitable to the web.  as an alternative, we propose a user-oriented approach based on the idea that the schema is a posteriori expressed by the user's needs when asking a query. given a user query, akira (agentive knowledge-based information retrieval architecture) [6] extracts a target structure (structure expressed in the query) and uses standard information retrieval and filtering techniques to access potentially relevant documents.  the user-oriented paradigm means that the structure through which the data is viewed does not come from the source but is extracted from the user query. when a user asks a query, the relevant information is retrieved from the web and stored as is in a cache. then the information is extracted from the raw data using computational linguistic techniques. the akira cache (smart-cache) represents these extracted layers of meta-information on top of the raw data. the smart-cache is an object-oriented database whose schema is inferred from the user's target structure. it is designed on demand through a library of concepts that can be assembled together to match concepts and meta-concepts required in the user's query. the smart cache can be seen as a view of the web.  to the best of our knowledge, akira is the only system that uses information retrieval and extraction integrated with database techniques to provide maximum flexibility to the user and offer transparent access to the content of web documents.  zoe lacroix arnaud sahuguet raman chandrasekar
a user-centered interface for querying distributed multimedia databases  facilitating information retrieval in the vastly growing realm of digital media has become increasingly difficult. delaunaymm seeks to assist all users in finding relevant information through an interactive interface that supports pre- and post-query refinement, and a customizable multimedia information display. this project leverages the strengths of visual query languages with a resourceful framework to provide users with a single intuitive interface. the interface and its supporting framework are described in this paper.  isabel f. cruz kimberly m. james
a decompositional approach to database constraint enforcement  this paper presents a decompositional approach to integrity constraint enforcement for very large database systems. the central theme of the paper is the development of the constraint decomposition theorem which can be used to decompose any complex constraint formula into a set of simpler constraint sub- formulas, each of which is a sufficient condition for the original constraint formula and they can be enforced independently of one another. by utilizing the decomposition theorem and the fact that both cost for checking each sub- formula and satisfiablity of each sub-formula may be different from one another, we developed a new constraint enforcement strategy which is much efficient than the previous approaches.  eugene y. sheng
the notification collage: posting information to public and personal displays  the notification collage (nc) is a groupware system where distributed and co- located colleagues comprising a small community post media elements onto a real-time collaborative surface that all members can see. akin to collages of information found on public bulletin boards, nc randomly places incoming elements onto this surface. people can post assorted media: live video from desktop cameras; editable sticky notes; activity indicator; slide shows displaying a series of digital photos, snapshots of a person's digitial desktop, and web page thumbnails. user experiences show that nc becomes a rich resource for awareness and collaboration. community members indicate their presence to others by posting live video. they regularly act on this information by engaging in text and video conversations. because all people can overhear conversations, these become active opportunities to join in. people also post items they believe will be interesting to others, such as desktop snapshots and vacation photos. finally, people use nc somewhat differently when it is displayed on a large public screen than when it appears on a personal computer.  saul greenberg michael rounding
the whips prototype for data warehouse creation and maintenance  a data warehouse is a repository of integrated information from distributed, autonomous, and possibly heterogeneous, sources. in effect, the warehouse stores one or more materialized views of the source data. the data is then readily available to user applications for querying and analysis. figure 1 shows the basic architecture of a warehouse: data is collected from each source, integrated with data from other sources, and stored at the warehouse. users then access the data directly from the warehouse.  as suggested by figure 1, there are two major components in a warehouse system: the integration component, responsible for collecting and maintaining the materialized views, and the query and analysis component, responsible for fulfilling the information needs of specific end users. note that the two components are not independent. for example, which views the integration component materializes depends on the expected needs of end users.  most current commercial warehousing systems (e.g., redbrick, sybase, arbor) focus on the query and analysis component, providing specialized index structures at the warehouse and extensive querying facilities for the end user. in the whips (warehousing information project at stanford) project, on the other hand, we focus on the integration component. in particular, we have developed an architecture and implemented a prototype for identifying data changes at heterogeneous sources, transforming them and summarizing them in accordance to warehouse specifications, and incrementally integrating them into the warehouse. we propose to demonstrate our prototype at sigmod, illustrating the main features of our architecture.  our architecture is modular and we designed it specifically to fulfill several important and interrelated goals: data sources and warehouse views can be added and removed dynamically; it is scalable by adding more internal modules; changes at the sources are detected automatically; the warehouse may be updated continuously as the sources change, without requiring "down time;" and the warehouse is always kept consistent with the source data by the integration algorithms. more details on these goals and how we achieve them are provided in [wgl+96].  wilburt j. labio yue zhuge janet l. wiener himanshu gupta hector garcia-molina jennifer widom
solving queries by tree projections  suppose a database schema d is extended to d  by adding new relation schemas, and states for d are extended to states for d  by applying joins and projections to existing relations. it is shown that certain desirable properties that d  has with respect to d. these properties amount to the ability to compute efficiently the join of all relations in a state for d from an extension of this state over d . the equivalence is proved for unrestricted (i.e., both finite and infinite) databases. if d  is obtained from d by adding a set of new relation schemas that form a tree schema, then the equivalence also holds for finite databases. in this case there is also a polynomial time algorithm for testing the existence of a tree projection of d  with respect to d.  yehoshua sagiv oded shmueli
organization of clustered files for consecutive retrieval  this paper studies the problem of storing single-level and multilevel clustered files. necessary and sufficient conditions for a single-level clustered file to have the consecutive retrieval property (crp) are developed. a linear time algorithm to test the crp for a given clustered file and to identify the proper arrangement of objects, if crp exists, is presented. for the single- level clustered files that do not have crp, it is shown that the problem of identifying a storage organization with minimum redundancy is np- complete.  consequently, an efficient heuristic algorithm to generate a good storage organization for such files is developed. furthermore, it is shown that, for certain types of multilevel clustered files, there exists a storage organization such that the objects in each cluster, for all clusters in each level of the clustering, appear in consecutive locations.  j s. deogun v v. raghavan t k.w. tsou
evaluation of remote backup algorithms for transaction processing systems  a remote backup is a copy of a primary database maintained at a geographically separate location and is used to increase data availability. remote backup systems are typically log-based and can be classified into 2-safe and 1-safe, depending on whether transactions commit at both sites simultaneously or they first commit at the primary and are later propagated to the backup. we have built an experimental database system on which we evaluated the performance of the epoch algorithm, a 1-safe algorithm we have developed, and compared it with the 2-safe approach under various conditions. we also report on the use of multiple log streams to propagate information from the primary to the backup.  christos a. polyzois hector garcia- molina
parallel processing and trusted database management systems  this paper applies parallel processing technology to database security technology and vice versa. we first describe the issues involved in incorporating multilevel security into parallel database management systems. in particular, we describe how multilevel security could be incorporated into the gamma architecture. then we describe the use of parallel architectures to perform trusted database management system functions. in particular, we describe security constraint processing in trusted database management systems and show how parallel processing could enhance the performance of this function.  bhavani thuraisingham william ford
a visual retrieval environment for hypermedia information systems  we present a graph-based object model that may be used as a uniform framework for direct manipulation of multimedia information. after an introduction motivating the need for abstraction and structuring mechanisms in hypermedia systems, we introduce the data model and the notion of perspective, a form of data abstraction that acts as a user interface to the system, providing control over the visibility of the objects and their properties. a perspective is defined to include an intension and an extension. the intension is defined in terms of a pattern, a subgraph of the schema graph, and the extension is the set of pattern-matching instances. perspectives, as well as database schema and instances, are graph structures that can be manipulated in various ways. the resulting uniform approach is well suited to a visual interface. a visual interface for complex information systems provides high semantic power, thus exploiting the semantic expressibility of the underlying data model, while maintaining ease of interaction with the system. in this way, we reach the goal of decreasing cognitive load on the user, with the additional advantage of always maintaining the same interaction style. we present a visual retrieval environment that effectively combines filtering, browsing, and navigation to provide an integrated view of the retrieval problem. design and implementation issues are outlined for more (multimedia object retrieval environment), a prototype system relying on the proposed model. the focus is on the main user interface functionalities, and actual interaction sessions are presented including schema creation, information loading, and information retrieval.  dario lucarella antonella zanzi
access methods for multiversion data  we present an access method designed to provide a single integrated index structure for a versioned timestamped database with a non-deletion policy. historical data (superceded versions) is stored separately from current data. our access method is called the time-split b-tree. it is an index structure based on malcolm easton's write once b-tree.  the write once b-tree was developed for data stored entirely on a write-once read-many or worm optical disk. the time-split b-tree differs from the write once b-tree in the following ways:  current data must be stored on an erasable random-access device.  historical data may be stored on any random-access device, including worms, erasable optical disks, and magnetic disks. the point is to use a faster and more expensive device for the current data and a slower cheaper device for the historical data.  the splitting policies have been changed to reduce redundancy in the structure ---the option of pure key splits as in b+-trees and a choice of split times for time-based splits enable this performance enhancement.  when data is migrated from the current to the historical database, it is consolidated and appended to the end of the historical database, allowing for high space utilization in worm disk sectors.  david lomet betty salzberg
office of the future: using the structure of the human communication system to build the office of the future (i)  the basic concept of the office of the future is a natural outgrowth of the expansion of computers helping people in business do what they could not, or would not, do. the presentation will be confined to describing how computers will be used to provide a technological linkage between the three parts of the human communication process and to clearly communicate complex financial information to all levels of management.  communication, or lack thereof, is one of the most serious problems constraining efficient business operations. the human communication system uses three basic input and output channels to pass information. these three channels---voice, the written word, and symbols--- provide a complete, sensitive and effective process that permits humans to communicate one with another. the system consists of a sender sending a message over one or more of the channels at a time, and the receiver receiving the message through one or more of the channels. the channels can and most often do have "static" in them caused by either the sender, the receiver or the channel. the static is more prevalent in business because different professional cultures have different vocabularies and customs. the result of the static is three levels of communication problems in business organizations:  irwin m. jarett
lof: identifying density-based local outliers  for many kdd applications, such as detecting criminal activities in e-commerce, finding the rare instances or the outliers, can be more interesting than finding the common patterns. existing work in outlier detection regards being an outlier as a binary property. in this paper, we contend that for many scenarios, it is more meaningful to assign to each object a _degree_ of being an outlier. this degree is called the _local outlier factor_ (lof) of an object. it is _local_ in that the degree depends on how isolated the object is with respect to the surrounding neighborhood. we give a detailed formal analysis showing that lof enjoys many desirable properties. using real-world datasets, we demonstrate that lof can be used to find outliers which appear to be meaningful, but can otherwise not be identified with existing approaches. finally, a careful performance evaluation of our algorithm confirms we show that our approach of finding local outliers can be practical.  markus m. breunig hans-peter kriegel raymond t. ng jörg sander
towards a framework for integrating multilevel secure models and temporal data models  within many organizations the number of databases containing classified or otherwise sensitive data is increasing rapidly. access to these databases must be restricted and controlled to limit the unauthorized disclosure, or malicious modification of data contained in them. however, the conventional models of authorization that have been designed for database systems supporting the hierarchical, network and relational models of data do not provide adequate mechanisms to support controlled access of temporal objects and context based temporal information. in this paper we extend the multilevel secure relational model to capture the functionality required of a temporal database, i.e. a database that supports some aspect of time, not counting user-defined time. in particular we assign class access to bitemporal timestamped attributes, and give explicit security classifications to temporal elements.  niki pissinou kia makki e. k. park
approximate ad-hoc query engine for simulation data  in this paper, we describe aqsim, an ongoing effort to design and impl ement a system to manage terabytes of scientific simulation data. the goal of this project is to reduce data storage requirements and access times while permitting ad-hoc queries using statistical and mathematical models of the data. in order to facilitate data exchange between models based on different representations, we are evaluating using the asci common data model that is comprised of several layers of increasing semantic complexity. to support queries over the spatial- temporal mesh structured data we are in the process of defining and implementing a grammar for meshsql  ghaleb abdulla chuck baldwin terence critchlow roy kamimura ida lozares ron musick nu ai tang byung s. lee robert snapp
efficient spatial data transmission in web-based gis  this paper has proposed a new method of efficient spatial data transmission in the client- side web-based gis (geographic information system) which handles large-size spatial geographic information on the internet. the basic idea is that, firstly, a largesize map is divided into several parts, where each part is called a "tile", according to appropriate division granularity. secondly, when an user requires a certain region in the map at client side, the gis server only transmits spatial data in the tiles which overlap with the requested region. and the received data are stored in client local machine for reuse. here a method of tile-division and tile-query processing has been provided. comparing with traditional client-side web-based gis, the performance improvement is achieved by the usage of the proposed method.  zu-kuan wei young-hwan oh jae-dong lee jae-hong kim dong-sun park young-geol lee hae-young bae
hci in the global knowledge-based economy: designing to support worker adaptation  increasingly, people are being required to perform open- ended intellectual tasks that require discretionary decision making. these demands require a relatively unique approach to the design of computer-based support tools. a review of the characteristics associated with the global knowledge-based economy strongly suggests that there will be an increasing need for workers, managers, and organizations to adapt to change and novelty. this is equivalent to a call for designing computer tools that foster continuous learning. there are reasons to believe that the need to support adaptation and continuous learning will only increase. thus, in the new millennium hci should be concerned with explicitly designing for worker adaptation. the cognitive work analysis framework is briefly described as a potential programmatic approach to this practical design challenge.  kim j. vicente
paperbuttons: expanding a tangible user interface  expanding the functionality of a successful system is always a challenge; the initial simplicity and ease-of-use is easily lost in the process. experience indicates that this problem is worsened in systems with tangible interfaces: while it might be relatively easy to suggest a single successful tangible interaction component, it is notoriously hard to preserve the success when expanding with more components or more manipulation using the same component. this paper describes our approach to creating and expanding tangible interfaces. the approach consist of adherence to a set of guidelines for tangible interfaces, derived from practical tangible design and general object-oriented design, and solicitation of user requirements to the particular interaction method in question. finally the paper describes a prototype of paperbuttons built in response to these requirements and designed in accordance to the guidelines for tangible interfaces.  elin rønby pedersen tomas sokoler les nelson