Hasan Davulcu

Logic based modeling and analysis of workflows

WC propose Concurrent Transaction Logic (C7X) as the language for specifying, analyzing, and scheduling of workflows. We show that both local and global properties of worktlows can be naturally represented as C7X formulas and reasoning can be done with the use of the proof theory and the semantics of this logic, We describe a transformation that leads to an eilicicnt algorithm for scheduling worldlows in the presencc of global temporal constraints, which leads to decision proccdurcs for dealing with several safety related properties such as whether every valid execution of the workflow satisfits a particular property or whether a worlcfiow execution is consistent with some given global constraints on the ordering of events in a workflow. We also provide tight complexity results on the running times of these algorithms.

A layered architecture for querying dynamic Web content

The design of webbases, database systems for supporting Web-based applications, is currently an active area of research. In this paper, we propose a 3-year architecture for designing and implementing webbases for querying dynamic Web content(i.e., data that can only be extracted by filling out multiple forms). The lowest layer, virtual physical layer, provides navigation independence by shielding the user from the complexities associated with retrieving data from raw Web sources. Next, the traditional logical layer supports site independence. The top layer is analogous to the external schema layer in traditional databases. Within this architectural framework we address two problems unique to webbases — retrieving dynamic Web content in the virtual physical layer and querying of the external schema by the end user. The layered architecture makes it possible to automate data extraction to a much greater degree than in existing proposals. Wrappers for the virtual physical schema can be created semi-automatically, by asking the webbase designer to navigate through the sites of interest — we call this approach mapping by example. Thus, the webbase designer need not have expertise in the language that maps the physical schema to the raw Web (this should be contrasted to other approaches, which require expertise in various Web-enabled flavors of SQL). For the external schema layer, we propose a semantic extension of the universal relation interface. This interface provides powerful, yet reasonably simple, ad hoc querying capabilities for the end user compared to the currently prevailing “canned” form-based interfaces on the one hand or complex Web-enabling extensions of SQL on the other. Finally, we discuss the implementation of the proposed architecture.

Modeling and analysis of interactions in virtual enterprises

Advances in computer networking technology and open system standards are making the creation and management of virtual enterprises feasible. A virtual enterprise is a temporary consortium of autonomous, diverse, and possibly geographically dispersed organizations that pool their resources to meet short-term objectives and exploit fast-changing market trends. For a virtual enterprise to succeed, its business processes must be automated, and its startup costs must be minimized. We describe a formal framework for modeling and reasoning about interactions in a virtual enterprise. Such a framework will form the basis for tools that provide automated support for creation and operation of virtual enterprises.

CTR-S: a logic for specifying contracts in semantic web services

A requirements analysis in the emerging field of Semantic Web Services (SWS) (see http://daml.org/services/swsl/requirements/) has identified four major areas of research: intelligent service discovery, automated contracting of services, process modeling, and service enactment. This paper deals with the intersection of two of these areas: process modeling as it pertains to automated contracting. Specifically, we propose a logic, called CTR-S,which captures the dynamic aspects of contracting for services.Since CTR-S is an extension of the classical first-order logic, it is well-suited to model the static aspects of contracting as well. A distinctive feature of contracting is that it involves two or more parties in a potentially adversarial situation. CTR-S is designed to model this adversarial situation through its novel model theory, which incorporates certain game-theoretic concepts. In addition to the model theory, we develop a proof theory for CTR-S and demonstrate the use of the logic formodeling and reasoning about Web service contracts.

IntEx: A Syntactic Role Driven Protein-Protein Interaction Extractor for Bio-Medical Text

In this paper, we present a fully automated extraction system, named IntEx, to identify gene and protein interactions in biomedical text. Our approach is based on first splitting complex sentences into simple clausal structures made up of syntactic roles. Then, tagging biological entities with the help of biomedical and linguistic ontologies. Finally, extracting complete interactions by analyzing the matching contents of syntactic roles and their linguistically significant combinations. Our extraction system handles complex sentences and extracts multiple and nested interactions specified in a sentence. Experimental evaluations with two other state of the art extraction systems indicate that the IntEx system achieves better performance without the labor intensive pattern engineering requirement.

Logic-Based Approaches to Workflow Modeling and Verification

A workflow is a collection of coordinated activities designed to carry out a well-defined complex process, such as trip planning, student registration, or a business process in a large enterprise. An activity in a workflow might be performed by a human, a device, or a program. Workflow management systems (or WfMS) provide a framework for capturing the interaction among the activities in a workflow and are recognized as a new paradigm for integrating disparate systems, including legacy systems. A large workflow system might involve many disparate activities that are coordinated in complex ways and are subject to many constraints. Thus, modeling such systems and ensuring that they perform according to the specifications is not an easy task. To be able to analyze the properties of workflows, the latter must be specified using a formalism with well-defined semantics. The popular formalisms in this area are the various logics, Petri Nets [1,35], Event-Condition-Action rules [23,15], and State Charts [36]. In this chapter we survey and compare a number of logic-based formalisms that were proposed in the literature.

ORTHOGONAL RANK-ONE MATRIX PURSUIT FOR LOW RANK MATRIX COMPLETION

In this paper, we propose an efficient and scalable low rank matrix completion algorithm. The key idea is to extend the orthogonal matching pursuit method from the vector case to the matrix case. We further propose an economic version of our algorithm by introducing a novel weight updating rule to reduce the time and storage complexity. Both versions are computationally inexpensive for each matrix pursuit iteration and find satisfactory results in a few iterations. Another advantage of our proposed algorithm is that it has only one tunable parameter, which is the rank. It is easy to understand and to use by the user. This becomes especially important in large-scale learning problems. In addition, we rigorously show that both versions achieve a linear convergence rate, which is significantly better than the previous known results. We also empirically compare the proposed algorithms with several state-of-the-art matrix completion algorithms on many real-world datasets, including the large-scale recommendati...

Information Extraction from Web Pages Using Presentation Regularities and Domain Knowledge

World Wide Web is transforming itself into the largest information resource making the process of information extraction (IE) from Web an important and challenging problem. In this paper, we present an automated IE system that is domain independent and that can automatically transform a given Web page into a semi-structured hierarchical document using presentation regularities. The resulting documents are weakly annotated in the sense that they might contain many incorrect annotations and missing labels. We also describe how to improve the quality of weakly annotated data by using domain knowledge in terms of a statistical domain model. We demonstrate that such system can recover from ambiguities in the presentation and boost the overall accuracy of a base information extractor by up to 20%. Our experimental evaluations with TAP data, computer science department Web sites, and RoadRunner document sets indicate that our algorithms can scale up to very large data sets.

Boosting Item Keyword Search with Spreading Activation

Most keyword search engines return directly matching keyword phrases. However, publishers cannot anticipate all possible ways in which users would search for the items in their documents. In fact, many times, there may be no direct keyword match between a keyword search phrase and descriptions of relevant items that are perfect matches for the search. We present an automated, high precision-based information retrieval solution to boost item find-ability by bridging the semantic gap between item information and popular keyword search phrases. Our solution achieves an average of 80% F-measure for various boosted matches for keyword search phrases in various categories.

Computational aspects of resilient data extraction from semistructured sources (extended abstract)

Automatic data extraction from semistructured sources such as HTML pages is rapidly growing into a problem of significant importance, spurred by the growing popularity of the so called “shopbots” that enable end users to compare prices of goods and other services at various web sites without having to manually browse and fill out forms at each one of these sites. The main problem one has to contend with when designing data extraction techniques is that the contents of a web page changes frequently, either because its data is generated dynamically, in response to filling out a form, or because of changes to its presentation format. This makes the problem of data extraction particularly challenging, since a desirable requirement of any data extraction technique is that it be “resilient”, i.e., using it we should always be able to locate the object of interest in a page (such as a form or an element in a table generated by a form fill-out) in spite of changes to the pages ntent and layout. In this paper we propose a formal computation model for developing resilient data extraction techniques from semistructured sources. Specifically we formalize the problem of data extraction as one of generating unambiguous extraction expressions, which are regular expressions with some additional structure. The problem of resilience is then formalized as one of generating a maximal extraction expression of this kind. We present characterization theorems for maximal extraction expressions, complexity results for testing them, and algorithms for synthesizing them.