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Data trees provide a standard abstraction of XML documents with data values: they are trees whose nodes, in addition to the usual labels, can carry labels from an infinite alphabet (data). Therefore, one is interested in decidable formalisms for reasoning about data trees. While some are known—such as the two-variable logic—they tend to be of… (More)
BACKGROUND There are limited reports of the use of whole exome sequencing (WES) as a clinical diagnostic tool. Moreover, there are no reports addressing the cost burden associated with genetic tests performed prior to WES. OBJECTIVE We demonstrate the performance characteristics of WES in a pediatric setting by describing our patient cohort, calculating… (More)
Let <i>D</i> denote an infinite alphabet -- a set that consists of infinitely many symbols. A word <i>w</i> = <i>a</i><sub>0</sub><i>b</i><sub>0</sub><i>a</i><sub>1</sub><i>b</i><sub>1</sub> ⋯ <i>a</i><sub>n</sub><i>b</i><sub>n</sub> of even length over <i>D</i> can be viewed as a directed graph <i>G</i><sub>w</sub> whose… (More)
In this paper we introduce a notion of a regular expression over infinite alphabets and show that a language is definable by an infinite alphabet regular expression if and only if it is acceptable by finite-state unification based automaton – a model of computation that is tightly related to other models of automata over infinite alphabets.
Dedicated to Boris (Boaz) Trakhtenbrot on the occasion of his 85 th birthday. Abstract. A number of models of computation on trees labeled with symbols from an infinite alphabet is considered. We study closure and decision properties of each of the models and compare their computation power.
In data words, each position carries not only a letter form a finite alphabet, as the usual words do, but also a data value coming from an infinite domain. There has been a renewed interest in them due to applications in querying and reasoning about data models with complex structural properties, notably XML, and more recently, graph databases. Logical… (More)
Previous studies of incomplete XML documents have identified three main sources of incompleteness -- in structural information, data values, and labeling -- and addressed data complexity of answering analogs of unions of conjunctive queries under the open world assumption. It is known that structural incompleteness leads to intractability, while… (More)
Data trees and data words have been studied extensively in connection with XML reasoning. These are trees or words that, in addition to labels from a finite alphabet, carry labels from an infinite alphabet (data). While in general logics such as MSO or FO are unde-cidable for such extensions, decidablity results for their fragments have been obtained… (More)
We introduce an automata model for data words, that is words that carry at each position a symbol from a finite alphabet and a value from an unbounded data domain. The model is (semantically) a restriction of data automata, introduced by Bojanczyk, et. al. in 2006, therefore it is called weak data automata. It is strictly less expressive than data automata… (More)
In this paper we study a subclass of pebble automata (PA) for data languages for which the emptiness problem is decidable. Namely, we show that the emptiness problem for weak 2-pebble automata is decid-able, while the same problem for weak 3-pebble automata is undecidable. We also introduce the so-called top view weak PA. Roughly speaking, top view weak PA… (More)