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14
Constraint Programming and Database Query Languages
 In Proc. 2nd Conference on Theoretical Aspects of Computer Software (TACS
, 1994
"... . The declarative programming paradigms used in constraint languages can lead to powerful extensions of Codd's relational data model. The development of constraint database query languages from logical database query languages has many similarities with the development of constraint logic programmin ..."
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Cited by 60 (3 self)
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. The declarative programming paradigms used in constraint languages can lead to powerful extensions of Codd's relational data model. The development of constraint database query languages from logical database query languages has many similarities with the development of constraint logic programming from logic programming, but with the additional requirements of data efficient, setatatime, and bottomup evaluation. In this overview of constraint query languages (CQLs) we first present the framework of [41]. The principal idea is that: "the ktuple (or record) data type can be generalized by a conjunction of quantifierfree constraints over k variables". The generalization must preserve various language properties of the relational data model, e.g., the calculus/algebra equivalence, and have time complexity polynomial in the size of the data. We next present an algebra for dense order constraints that is simpler to evaluate than the calculus described in [41], and we sharpen some of...
The Expressiveness of a Family of Finite Set Languages
 IN PROCEEDINGS OF 10TH ACM SYMPOSIUM ON PRINCIPLES OF DATABASE SYSTEMS
, 1991
"... In this paper we characterise exactly the complexity of a set based database language called SRL, which presents a unified framework for queries and updates. By imposing simple syntactic restrictions on it, we are able to express exactly the classes, P and LOGSPACE. We also discuss the role of orde ..."
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Cited by 26 (3 self)
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In this paper we characterise exactly the complexity of a set based database language called SRL, which presents a unified framework for queries and updates. By imposing simple syntactic restrictions on it, we are able to express exactly the classes, P and LOGSPACE. We also discuss the role of ordering in database query languages and show that the hom operator of Machiavelli language in [OBB89] does not capture all the orderindependent properties.
Database Query Languages Embedded in the Typed Lambda Calculus
, 1993
"... We investigate the expressive power of the typed calculus when expressing computations over finite structures, i.e., databases. We show that the simply typed calculus can express various database query languages such as the relational algebra, fixpoint logic, and the complex object algebra. In ..."
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Cited by 25 (6 self)
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We investigate the expressive power of the typed calculus when expressing computations over finite structures, i.e., databases. We show that the simply typed calculus can express various database query languages such as the relational algebra, fixpoint logic, and the complex object algebra. In our embeddings, inputs and outputs are terms encoding databases, and a program expressing a query is a term which types when applied to an input and reduces to an output.
Constraint Databases: A Survey
 Semantics in Databases, number 1358 in LNCS
, 1998
"... . Constraint databases generalize relational databases by finitely representable infinite relations. This paper surveys the state of the art in constraint databases: known results, remaining open problems and current research directions. The paper also describes a new algebra for databases with inte ..."
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Cited by 23 (3 self)
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. Constraint databases generalize relational databases by finitely representable infinite relations. This paper surveys the state of the art in constraint databases: known results, remaining open problems and current research directions. The paper also describes a new algebra for databases with integer order constraints and a complexity analysis of evaluating queries in this algebra. In memory of Paris C. Kanellakis 1 Introduction There is a growing interest in recent years among database researchers in constraint databases, which are a generalization of relational databases by finitely representable infinite relations. Constraint databases are parametrized by the type of constraint domains and constraint used. The good news is that for many parameters constraint databases leave intact most of the fundamental assumptions of the relational database framework proposed by Codd. In particular, 1. Constraint databases can be queried by constraint query languages that (a) have a semantics ba...
Extensible Query Processing in an ObjectOriented Database
, 1993
"... In this thesis we address the problem of providing efficient processing of queries in the extensible environment induced by objectoriented databases. We define a framework for query processing in an objectoriented database and develop designs for major components of this framework. The framework e ..."
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Cited by 21 (1 self)
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In this thesis we address the problem of providing efficient processing of queries in the extensible environment induced by objectoriented databases. We define a framework for query processing in an objectoriented database and develop designs for major components of this framework. The framework encompasses an objectoriented data model, an algebra to query over that model, transformation rules for the algebra, an internal representation for queries expressed in the algebra, a cost model for analyzing query expressions, and an architecture for an extensible query optimizer. The major contributions of this thesis are an algebra and transformation rules, a representation, and an architecture for extensible query optimization. We show how these components fit into the framework and interact with each other. The EQUAL query algebra presented in this thesis is the first query algebra for objectoriented database systems to be completely consistent with data abstraction, and one of the few...
Comprehension Syntax
 SIGMOD RECORD
, 1994
"... The syntax of comprehensions is very close to the syntax of a number of practical database query languages and is, we believe, a better starting point than firstorder logic for the development of database languages. We give an informal account of a language based on comprehension syntax that deals ..."
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Cited by 19 (4 self)
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The syntax of comprehensions is very close to the syntax of a number of practical database query languages and is, we believe, a better starting point than firstorder logic for the development of database languages. We give an informal account of a language based on comprehension syntax that deals uniformly with a variety of collection types; it also includes pattern matching, variant types and function definition. We show, again informally, how comprehension syntax is a natural fragment of structural recursion, a much more powerful programming paradigm for collection types. We also show that a very small "abstract syntax language" can serve as a basis for the implementation and optimization of comprehension syntax.
On Two Forms of Structural Recursion
 in "LNCS 893: Proceedings of 5th International Conference on Database Theory," 111124
, 1995
"... . We investigate and compare two forms of recursion on sets for querying nested collections. The first one is called sri and it corresponds to sequential processing of data. The second one is called sru and it corresponds to dataparallel processing. A uniform firstorder translation from sru into s ..."
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Cited by 19 (13 self)
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. We investigate and compare two forms of recursion on sets for querying nested collections. The first one is called sri and it corresponds to sequential processing of data. The second one is called sru and it corresponds to dataparallel processing. A uniform firstorder translation from sru into sri was known from previous work. The converse translation is by necessity more difficult and we have obtained three main results concerning it. First, we exhibit a uniform translation of sri queries into sru queries over the nested relational algebra. We observe that this translation maps PTIME algorithms into exponentialspace queries. The second result proves that any uniform translation of sri queries into sru queries over the nested relational algebra must map some PTIME queries into exponentialspace ones. In fact, in the presence of certain external functions, we provide a PTIME sri query for which any equivalent sru query requires exponential space. Thus, as a mechanism for implemen...
Higher Order Logic
 In Handbook of Logic in Artificial Intelligence and Logic Programming
, 1994
"... Contents 1 Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 2 The expressive power of second order Logic : : : : : : : : : : : 3 2.1 The language of second order logic : : : : : : : : : : : : : 3 2.2 Expressing size : : : : : : : : : : : : : : : : : : : : : : : : 4 2.3 Definin ..."
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Cited by 19 (0 self)
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Contents 1 Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 2 The expressive power of second order Logic : : : : : : : : : : : 3 2.1 The language of second order logic : : : : : : : : : : : : : 3 2.2 Expressing size : : : : : : : : : : : : : : : : : : : : : : : : 4 2.3 Defining data types : : : : : : : : : : : : : : : : : : : : : 6 2.4 Describing processes : : : : : : : : : : : : : : : : : : : : : 8 2.5 Expressing convergence using second order validity : : : : : : : : : : : : : : : : : : : : : : : : : 9 2.6 Truth definitions: the analytical hierarchy : : : : : : : : 10 2.7 Inductive definitions : : : : : : : : : : : : : : : : : : : : : 13 3 Canonical semantics of higher order logic : : : : : : : : : : : : 15 3.1 Tarskian semantics of second order logic : : : : : : : : : 15 3.2 Function and re
Functional Database Query Languages as Typed Lambda Calculi of Fixed Order (Extended Abstract)
 In Proceedings 13th PODS
, 1994
"... We present a functional framework for database query languages, which is analogous to the conventional logical framework of firstorder and fixpoint formulas over finite structures. We use atomic constants of order 0, equality among these constants, variables, application, lambda abstraction, and le ..."
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Cited by 12 (5 self)
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We present a functional framework for database query languages, which is analogous to the conventional logical framework of firstorder and fixpoint formulas over finite structures. We use atomic constants of order 0, equality among these constants, variables, application, lambda abstraction, and let abstraction; all typed using fixed order ( 5) functionalities. In this framework, proposed in [21] for arbitrary order functionalities, queries and databases are both typed lambda terms, evaluation is by reduction, and the main programming technique is list iteration. We define two families of languages: TLI = i or simplytyped list iteration of order i +3 with equality, and MLI = i or MLtyped list iteration of order i+3 with equality; we use i+3 since our list representation of databases requires at least order 3. We show that: FOqueries ` TLI = 0 ` MLI = 0 ` LOGSPACEqueries ` TLI = 1 = MLI = 1 = PTIMEqueries ` TLI = 2 , where equality is no longer a primitive in TLI = 2 . We also show that ML type inference, restricted to fixed order, is polynomial in the size of the program typed. Since programming by using low order functionalities and type inference is common in functional languages, our results indicate that such programs suffice for expressing efficient computations and that their MLtypes can be efficiently inferred.
Finite Model Theory In The Simply Typed Lambda Calculus
, 1994
"... Church's simply typed calculus is a very basic framework for functional programming language research. However, it is common to augment this framework with additional programming constructs, because its expressive power for functions over the domain of Church numerals is very limited. In this thesi ..."
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Cited by 8 (5 self)
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Church's simply typed calculus is a very basic framework for functional programming language research. However, it is common to augment this framework with additional programming constructs, because its expressive power for functions over the domain of Church numerals is very limited. In this thesis: (1) We reexamine the expressive power of the "pure" simply typed calculus, but over encodings of finite relational structures, i. e., finite models or databases . In this novel framework the simply typed calculus expresses all elementary functions from finite models to finite models. In addition, many common database query languages, e. g., relational algebra, Datalog : , and the Abiteboul/Beeri complex object algebra, can be embedded into it. The embeddings are feasible in the sense that the terms corresponding to PTIME queries can be evaluated in polynomial time. (2) We examine fixedorder fragments of the simply typed calculus to determine machine independent characterizations of complexity classes. For this we augment the calculus with atomic constants and equality among atomic constants. We show that over ordered structures, the order 3, 4, 5, and 6 fragments express exactly the firstorder, PTIME, PSPACE, and EXPTIME queries, respectively, and we conjecture that for general k 1, order 2 k + 4 expresses exactly the kEXPTIME queries and order 2 k + 5 expresses exactly the kEXPSPACE queries. (3) We also reexamine other functional characterizations of PTIME and we show that method schemas with ordered objects express exactly PTIME. This is a firstorder framework proposed for objectoriented databasesas opposed to the above higherorder frameworks. In summary, this research provides a link between finite model theory (and thus computational complexity), dat...