Concepts inOn the aggregation problem for synthesized web services
Aggregation problem
An aggregate in economics is a summary measure describing a market or economy. The aggregation problem refers to the difficulty of treating an empirical or theoretical aggregate as if it reacted like a less-aggregated measure, say, about behavior of an individual agent as described in general microeconomic theory. Examples of aggregates in micro- and macroeconomics relative to less aggregated counterparts are: food vs. apples the price level and real GDP vs.
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Web service
A Web service is a method of communication between two electronic devices over the Web. The W3C defines a "Web service" as "a software system designed to support interoperable machine-to-machine interaction over a network". It has an interface described in a machine-processable format (specifically Web Services Description Language, known by the acronym WSDL).
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Cycle (graph theory)
In graph theory, the term cycle may refer to a closed path. If repeated vertices are allowed, it is more often called a closed walk. If the path is a simple path, with no repeated vertices or edges other than the starting and ending vertices, it may also be called a simple cycle, circuit, circle, or polygon; see Cycle graph. A cycle in a directed graph is called a directed cycle. The term cycle may also refer to: An element of the binary or integral (or real, complex, etc.
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PSPACE
In computational complexity theory, PSPACE is the set of all decision problems which can be solved by a Turing machine using a polynomial amount of space.
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Directed acyclic graph
In mathematics and computer science, a directed acyclic graph, is a directed graph with no directed cycles. That is, it is formed by a collection of vertices and directed edges, each edge connecting one vertex to another, such that there is no way to start at some vertex v and follow a sequence of edges that eventually loops back to v again. DAGs may be used to model several different kinds of structure in mathematics and computer science.
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Graph embedding
In topological graph theory, an embedding (also spelled imbedding) of a graph on a surface ¿ is a representation of on ¿ in which points of ¿ are associated to vertices and simple arcs (homeomorphic images of) are associated to edges in such a way that: the endpoints of the arc associated to an edge are the points associated to the end vertices of, no arcs include points associated with other vertices, two arcs never intersect at a point which is interior to either of the arcs.
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NP (complexity)
In computational complexity theory, NP is one of the most fundamental complexity classes. The abbreviation NP refers to "nondeterministic polynomial time. " Intuitively, NP is the set of all decision problems for which the instances where the answer is "yes" have efficiently verifiable proofs of the fact that the answer is indeed "yes. " More precisely, these proofs have to be verifiable in polynomial time by a deterministic Turing machine.
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Directed graph
In mathematics, a directed graph or digraph is a graph, or set of nodes connected by edges, where the edges have a direction associated with them. In formal terms a digraph is a pair (sometimes) of: a set V, whose elements are called vertices or nodes, a set A of ordered pairs of vertices, called arcs, directed edges, or arrows (and sometimes simply edges with the corresponding set named E instead of A).
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