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. The relational model, as proposed by Codd, contained the concept of relations as tables composed of tuples of single valued attributes taken from a domain. In most of the early literature this domain was assumed to consist of elementary items such as simple (atomic) values, dened complex data types or arbitrary length binary objects. Subsequent to that the nested relational or non-rst normal form model allowing set-valued or relation-valued attributes was proposed. Within this model an attribute could take multiple values or complete relations as values. This paper presents a further extension to the relational model which allows domains to be dened as a hierarchy (specically a lattice) of concepts, shows how dierent types of imperfect knowledge can be represented in attributes dened over such domains, and demonstrates how lattices allow the accommodation of some forms of inductive queries. While our model is applied to at relations, many of the results given are applicable also to nested relations. Necessary extensions to the relational algebra and SQL, a justication for the extension in terms of application areas and future research areas are also discussed. 1

The PESKI (Probabilities, Expert Systems, Knowledge, and Inference) system attempts to address some of the problems in expert system design through the use of the Bayesian Knowledge Base (BKB) representation.

A typical framework of sensor streams is data obtained from wireless networks of sensors, embedded in a physical space, continuously communicating a stream of data to a database. These wireless networks typically consist of large number of low-power and limited-bandwidth devices. They are primarily used for monitoring of several physical phenomenon such as, contamination, climate, building structure, etc., potentially in remote harsh environments. Research in sensor streaming has been generally focused on ultimate utilization of such devices given their limited resources and unattended deployment. This paper surveys current research directions in sensor data streams. In particular, it emphasizes existing work on storage and gathering of sensor data, architectures for querying sensor streams, and handling of erroneous sensors. It also highlights some open problems and discusses research paths to pursue in this exciting research area. 1

The relational model, as proposed by Codd, contained the concept of relations as tables composed of tuples of single valued attributes taken from a domain. In most of the early literature this domain was assumed to consist of elementary items such as simple (atomic) values, defined complex data types or arbitrary length binary objects. Subsequently the nested relational or non-first normal form model allowing set-valued or relation-valued attributes was proposed. Within this model an attribute could takemultiple values or complete relations as values. This paper presents a further extension to the relational model which allows domains to be defined as a hierarchy (specifically a lattice) of concepts, shows how differenttypes of imperfect knowledge can be represented in attributes defined over such domains, and demonstrates how lattices allow the accommodation of some forms of inductive queries. While our model is applied to flat relations, many of the results given are applicable also to nested relations. Necessary extensions to the relational algebra and the query language SQL are also discussed. Keywords: Inductive queries, concept lattices, imperfect information in databases, incomplete information, inconsistency, imprecision. 1

Conventional search engines find Web pages by using keyword matching. Two disadvantages for keyword matching are: (i) the order of keywords is ignored; and (ii) the approximate queries submitted by users are beyond the method of keyword matching can handle. Using keyword matching for Web page search is not satisfactory. This paper proposes a Web search system, named ApproxSeek, to facilitate Web information retrieval. The ApproxSeek achieves better search results by comparing the longest approximate common subsequences, which are the modified longest common subsequences having fault-tolerance capability. Experimental data show the proposed method improves the Web search, though more tests need to be conducted in order to support the conclusion. 1 Introduction The Web is a hyper-multimedia body of approximately 800 million pages that continues to grow at roughly a million pages per day [5]. How to retrieve information from the growing Web is a critical issue for the effectiveness of We...

A null value whose exact value exists but is not currently available is termed unknown value in database context. This paper proposes a construct called IP(Implicit Predicate) to handle the unknown values in fuzzy databases including disjunctive information. IP is basically a descriptor associated with an attribute for describing the subtle semantics of the unknown values occurring in the attribute. In this paper we show that the IP construct is a powerful data type capable of not only greatly enhancing the semantic expressiveness of the unknown values, but also incorporating thesauri into databases to perform concept-based match when evaluating queries. The semantic expressiveness of IP includes the capability of effectively exploiting disjunctive fuzzy information as well as representing it. We also propose a query evaluation mechanism involving this IPs to extract exact answers from the disjunctive fuzzy information. Keywords: Null Values, Fuzzy Databases, Query Evaluation 2 1. I...

The problem of imperfect information in intelligent systems is handled in two distinctive ways: 1) symbolically, in the case of incomplete information, and 2) numerically, in the case of imprecise and uncertain information. Symbolic methods are based upon extensions to classical logic, while numerical methods employ quantifiers that may propagate over a network representing dependencies between relevant facts. The paper will concentrate on the network models to represent uncertainty, following the idea of adjusting some underlying probability distribution which makes particular options the correct conclusions. One of the problems with network models is their inherent complex abstraction. The paper will analyze all requirements for a visual probabilistic dependency network design environment, suitable for numerical uncertainty management. A specific object oriented framework will be revealed and discussed. I. INTRODUCTION The purpose of information systems is to model (represent and r...

this paper was written, the use of null values was widespread. Indeed, the rst use of null values in the context of relational algebra was contained in a paper written by Codd in 1975 paper [3], and the ANSI/X3/SPARC interim report [1] published the same year included 14 dierent ways in which null values might be interpreted suggesting wide acceptance of their use. The omissions were various. The most serious was that of the work of Grant, who was working on the problem of incomplete information as early as 1974 [8], and who took Codd's initial results on null values in relational algebra and extended them considerably. The rst extension [7] involved a slight alteration to Codd's three-valued logic to ensure that it retrieved the right tuples in all situations. The next extension [6] was to handle what Grant calls "partial values", that is values which are known to lie in an interval and so are partially determined, and this idea was further developed in [5]. This line of research

Introduction Extant tools currently available for formal modeling, reasoning, decision making and computation in computer engineering are unequivocal, that is, they contains no uncertainties. Certainty indicates that the structures and parameters of the model they are dealing with is assumed to be precisely and totally known, and thus there are no doubts about their values, occurrence and their completeness. However, unfortunately, in our real life application domains, there is an unavoidable and uncontrollable loss of information and a discrepancy-our real word is full of uncertainties [Deyi90]. ' The term 'uncertainty' has a broad semantic content. According to Webste's New Twentieth Century Dictionary, six different interpretations of this term are possible. 1. Not certainly known; questionable; problematical. 2. Vague; not definite or determined. 3. Doubtful; not having certain knowledge; not sure. 4. Ambiguous. 5. Not steady or constant; varying. 6. Liable to change or