How Many Variables are Needed to Express an Existential Positive Query?
نویسندگان
چکیده
منابع مشابه
How Many Variables Are Needed to Express an Existential Positive Query?
The number of variables used by a first-order query is a fundamental measure which has been studied in numerous contexts, and which is known to be highly relevant to the task of query evaluation. In this article, we study this measure in the context of existential positive queries. Building on previous work, we present a combinatorial quantity defined on existential positive queries; we show th...
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ژورنال
عنوان ژورنال: Theory of Computing Systems
سال: 2018
ISSN: 1432-4350,1433-0490
DOI: 10.1007/s00224-018-9884-z