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The university course timetabling problem (UCTP) is a combinatorial optimization problem, in which a set of events has to be scheduled into time slots and located into suitable rooms. The design of course timetables for academic institutions is a very difficult task because it is an NP-hard problem. This paper investigates genetic algorithms (GAs) with a guided search strategy and local search (LS)...
The satisfiability problem (SAT) is shown to be the first decision NP-complete problem. It is central in complexity theory. A CNF formula usually contains an interesting number of symmetries. That is, the formula remains invariant under some variable permutations. Such permutations are the symmetries of the formula, their elimination can lead to make a short proof for a satisfiability proof procedure...
In this paper we show how the complexity of performing nearest neighbor (NNS) search on a metric space is related to the expansion of the metric space. Given a metric space we look at the graph obtained by connecting every pair of points within a certain distance r. We then look at various notions of expansion in this graph relating them to the cell probe complexity of NNS for randomized and deterministic,...
A developed Dijkstra shortest path search algorithm is proposed through improving data structure, preprocessing to remove redundant vertices and setting the search region sequence. The average running time before and after improvement is compared and analyzed through the simulation tests. The results show that the developed Dijkstra shortest path search algorithm can improve storage efficiency and...
Abstract-We consider the I/O-efficient rectangular segment search problem in 2D. The problem involves storing a given set S of N line segments in a data structure such that an axis aligned rectangular range query R can be performed efficiently; i.e., report all line segments in S which intersect R. We give a data structure requiring space O(N(N/B)2) disk blocks that can answer a range query R using...
This paper addresses the problem of finding the nearest neighbor (or one of the R-nearest neighbors) of a query object in a database which is only accessible through a comparison oracle. The comparison oracle, given two reference objects and a query object, returns the reference object closest to the query object. The oracle attempts to model the behavior of human users, capable of making statements...
Fixed spectrum frequency assignment problem, known as a NP-hard problem, is frequencies available are fixed and the goal is to minimize the interference due to the reuse of frequencies. The problem is still very important in wireless communication networks. An improved heuristic method, tabu search with a special data structure named single-frequency violation and an initialization strategy along...
Dynamic connectivity is a well-studied problem, but so far the most compelling progress has been confined to the edge-update model: maintain an understanding of connectivity in an undirected graph, subject to edge insertions and deletions. In this paper, we study two more challenging, yet equally fundamental problems: subgraph connectivity asks to maintain an understanding of connectivity under vertex...
This work investigates a geometric approach to proving cell probe lower bounds for data structure problems.We consider the {\em approximate nearest neighbor search problem} on the Boolean hypercube $(\bool^d,\onenorm{\cdot})$ with $d=\Theta(\log n)$. We show that any (randomized) data structure for the problem that answers $c$-approximate nearest neighbor search queries using probes must use space...
Heterogeneous multiprocessor systems, assembled with off-the-shelf processors and augmented with reprogrammable devices, thanks to their performance, cost effectiveness and flexibility, have become a standard platform for embedded systems. To fully exploit the computational power offered by these systems, great care should be taken when deciding on which processing element (mapping) and when (scheduling)...
Two decision problems are presented that arise from reversing the operation of a distance-based indexing tree. Whereas similarity search finds points in the tree given a query point, reverse similarity search begins with a set of constraints like those defining a leaf and generates a point meeting the constraints. These problems derive from robust hashing, a technique used in similarity search and...
In this paper, a new data structure called string-queue is proposed in order to implement more efficiently the selection rule and the elimination rule of the general branch-and-bound algorithm. A new general parallel branch-and-bound algorithm on a distributed memory multiprocessor system is also presented. Its communication complexity in single iteration is down to its lower bound O(p) on a 2D mesh...
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