Aybar C. Acar

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A virtual database system is software that provides unified access to multiple information sources. If the sources are <i>overlapping</i> in their contents and <i>independently</i> maintained, then the likelihood of <i>inconsistent</i> answers is high. Solutions are often based on ranking (which sorts the different answers according to recurrence) and on(More)
Agent Academy (AA) aims to develop a multi-agent society that can train new agents for specific or general tasks, while constantly retraining existing agents in a recursive mode. The system is based on collecting information both from the environment and the behaviors of the acting agents and their related successes/failures to generate a body of data,(More)
A sequence of queries submitted by a database user within a short period of time may have a single, illuminating explanation. In this paper we consider sequences of single-record queries, and attempt to guess what information their authors may be trying to accumulate. Query sequences may reflect clandestine intentions, where users attempt to avoid direct(More)
microRNA expression and sequence analysis database (http://konulab.fen.bilkent.edu.tr/mirna/) (mESAdb) is a regularly updated database for the multivariate analysis of sequences and expression of microRNAs from multiple taxa. mESAdb is modular and has a user interface implemented in PHP and JavaScript and coupled with statistical analysis and visualization(More)
Finding intensional encapsulations of database subsets is the inverse of query evaluation. Whereas query evaluation transforms an in-tensional expression (the query) to its extension (a set of data values), intensional encapsulation assigns an intensional expression to a given set of data values. We describe a method for deriving intensional representations(More)
We introduce the problem of query consolidation, which seeks to interpret a set of disparate queries submitted to independent databases with a single " global " query. This problem has multiple applications, from improving database design to protecting information from a seemingly innocuous set of apparently unrelated queries. The problem exhibits(More)
Recent developments in high-throughput technologies have been very helpful towards understanding the molecular abnormalities observed in disease conditions such as cancer. High-throughput experiments, which provide transcriptome-wide expression information for a cell give better insight into understanding the differences of biological processes between(More)
When gathering information from multiple independent data sources, users will generally pose a sequence of queries to each source, combine (union) or cross-reference (join) the results in order to obtain the information they need. Furthermore, when gathering information, there is a fair bit of trial and error involved, where queries are recursively refined(More)
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