Results 1  10
of
127
Linear Types and NonSizeIncreasing Polynomial Time Computation
 Information and Computation
, 1998
"... this paper we present a typetheoretic approach to this problem. We will develop a fairly natural linear type system which has the property that all definable functions are nonsize increasing and which boasts higherorder recursion on datatypes without any predicativity restriction. We will show th ..."
Abstract

Cited by 69 (12 self)
 Add to MetaCart
this paper we present a typetheoretic approach to this problem. We will develop a fairly natural linear type system which has the property that all definable functions are nonsize increasing and which boasts higherorder recursion on datatypes without any predicativity restriction. We will show that nevertheless all definable firstorder functions are polynomial time computable even if they contain higherorder functions as subexpressions
Optimizing Object Queries Using an Effective Calculus
 ACM Transactions on Database Systems
, 1998
"... This paper concentrates on query unnesting (also known as query decorrelation), an optimization that, even though improves performance considerably, is not treated properly (if at all) by most OODB systems. Our framework generalizes many unnesting techniques proposed recently in the literature and i ..."
Abstract

Cited by 45 (2 self)
 Add to MetaCart
This paper concentrates on query unnesting (also known as query decorrelation), an optimization that, even though improves performance considerably, is not treated properly (if at all) by most OODB systems. Our framework generalizes many unnesting techniques proposed recently in the literature and is capable of removing any form of query nesting using a very simple and efficient algorithm. The simplicity of our method is due to the use of the monoid comprehension calculus as an intermediate form for OODB queries. The monoid comprehension calculus treats operations over multiple collection types, aggregates, and quantifiers in a similar way, resulting in a uniform way of unnesting queries, regardless of their type of nesting.
Predicative Recursion and Computational Complexity
, 1992
"... The purpose of this thesis is to give a "foundational" characterization of some common complexity classes. Such a characterization is distinguished by the fact that no explicit resource bounds are used. For example, we characterize the polynomial time computable functions without making any direct r ..."
Abstract

Cited by 45 (3 self)
 Add to MetaCart
The purpose of this thesis is to give a "foundational" characterization of some common complexity classes. Such a characterization is distinguished by the fact that no explicit resource bounds are used. For example, we characterize the polynomial time computable functions without making any direct reference to polynomials, time, or even computation. Complexity classes characterized in this way include polynomial time, the functional polytime hierarchy, the logspace decidable problems, and NC. After developing these "resource free" definitions, we apply them to redeveloping the feasible logical system of Cook and Urquhart, and show how this firstorder system relates to the secondorder system of Leivant. The connection is an interesting one since the systems were defined independently and have what appear to be very different rules for the principle of induction. Furthermore it is interesting to see, albeit in a very specific context, how to retract a second order statement, ("inducti...
Resource Control for Synchronous Cooperative Threads
 In CONCUR, volume 3170 of LNCS
, 2004
"... We develop new methods to statically bound the resources needed for the execution of systems of concurrent, interactive threads. ..."
Abstract

Cited by 34 (4 self)
 Add to MetaCart
We develop new methods to statically bound the resources needed for the execution of systems of concurrent, interactive threads.
A Linguistic Characterization of Bounded Oracle Computation and Probabilistic Polynomial Time
, 1998
"... We present a higherorder functional notation for polynomialtime computation with an arbitrary 0, 1valued oracle. This formulation provides a linguistic characterization for classes such as NP and BPP, as well as a notation for probabilistic polynomialtime functions. The language is derived from H ..."
Abstract

Cited by 26 (9 self)
 Add to MetaCart
We present a higherorder functional notation for polynomialtime computation with an arbitrary 0, 1valued oracle. This formulation provides a linguistic characterization for classes such as NP and BPP, as well as a notation for probabilistic polynomialtime functions. The language is derived from Hofmann 's adaptation of BellantoniCook safe recursion, extended to oracle computation via work derived from that of Kapron and Cook. Like Hofmann's language, ours is an applied typed lambda calculus with complexity bounds enforced by a type system. The type system uses a modal operator to distinguish between two sorts of numerical expressions. Recursion can take place on only one of these sorts. The proof that the language captures precisely oracle polynomial time is modeltheoretic, using adaptations of various techniques from category theory.
Efficient First Order Functional Program Interpreter With Time Bound Certifications
, 2000
"... We demonstrate that the class of rst order functional programs over lists which terminate by multiset path ordering and admit a polynomial quasiinterpretation, is exactly the class of function computable in polynomial time. The interest of this result lies (i) on the simplicity of the conditions on ..."
Abstract

Cited by 25 (10 self)
 Add to MetaCart
We demonstrate that the class of rst order functional programs over lists which terminate by multiset path ordering and admit a polynomial quasiinterpretation, is exactly the class of function computable in polynomial time. The interest of this result lies (i) on the simplicity of the conditions on programs to certify their complexity, (ii) on the fact that an important class of natural programs is captured, (iii) and on potential applications on program optimizations. 1 Introduction This paper is part of a general investigation on the implicit complexity of a specication. To illustrate what we mean, we write below the recursive rules that computes the longest common subsequences of two words. More precisely, given two strings u = u1 um and v = v1 vn of f0; 1g , a common subsequence of length k is dened by two sequences of indices i 1 < < i k and j1 < < jk satisfying u i q = v j q . lcs(; y) ! 0 lcs(x; ) ! 0 lcs(i(x); i(y)) ! lcs(x; y) + 1 lcs(i(...
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 ..."
Abstract

Cited by 25 (6 self)
 Add to MetaCart
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.
Sequences, Datalog and Transducers
, 1996
"... This paper develops a query language for sequence databases, such as genome databases and text databases. The language, called SequenceDatalog, extends classical Datalog with interpreted function symbols for manipulating sequences. It has both a clear operational and declarative semantics, based on ..."
Abstract

Cited by 24 (5 self)
 Add to MetaCart
This paper develops a query language for sequence databases, such as genome databases and text databases. The language, called SequenceDatalog, extends classical Datalog with interpreted function symbols for manipulating sequences. It has both a clear operational and declarative semantics, based on a new notion called the extended active domain of a database. The extended domain contains all the sequences in the database and all their subsequences. This idea leads to a clear distinction between safe and unsafe recursion over sequences: safe recursion stays inside the extended active domain, while unsafe recursion does not. By carefully limiting the amountof unsafe recursion, the paper develops a safe and expressive subset of Sequence Datalog. As part of the development, a new type of transducer is introduced, called a generalized sequence transducer. Unsafe recursion is allowed only within these generalized transducers. Generalized transducers extend ordinary transducers by allowing them to invoke other transducers as "subroutines." Generalized transducers can be implemented in Sequence Datalog in a straightforward way. Moreover, their introduction into the language leads to simple conditions that guarantee safety and finiteness. This paper develops two such conditions. The first condition expresses exactly the class of ptime sequence functions; and the second expresses exactly the class of elementary sequence functions.
The Expressive Power of Higherorder Types or, Life without CONS
, 2001
"... Compare firstorder functional programs with higherorder programs allowing functions as function parameters. Can the the first program class solve fewer problems than the second? The answer is no: both classes are Turing complete, meaning that they can compute all partial recursive functions. In pa ..."
Abstract

Cited by 24 (1 self)
 Add to MetaCart
Compare firstorder functional programs with higherorder programs allowing functions as function parameters. Can the the first program class solve fewer problems than the second? The answer is no: both classes are Turing complete, meaning that they can compute all partial recursive functions. In particular, higherorder values may be firstorder simulated by use of the list constructor ‘cons’ to build function closures. This paper uses complexity theory to prove some expressivity results about small programming languages that are less than Turing complete. Complexity classes of decision problems are used to characterize the expressive power of functional programming language features. An example: secondorder programs are more powerful than firstorder, since a function f of type [Bool]〉Bool is computable by a consfree firstorder functional program if and only if f is in PTIME, whereas f is computable by a consfree secondorder program if and only if f is in EXPTIME. Exact characterizations are given for those problems of type [Bool]〉Bool solvable by programs with several combinations of operations on data: presence or absence of constructors; the order of data values: 0, 1, or higher; and program control structures: general recursion, tail recursion, primitive recursion.