Amir Nayyeri

Minimum cuts and shortest homologous cycles

We describe the first algorithms to compute minimum cuts in surface-embedded graphs in near-linear time. Given an undirected graph embedded on an orientable surface of genus g, with two specified vertices s and t, our algorithm computes a minimum (s,t)-cut in gO(g) n log n time. Except for the special case of planar graphs, for which O(n log n)-time algorithms have been known for more than 20 years, the best previous time bounds for finding minimum cuts in embedded graphs follow from algorithms for general sparse graphs. A slight generalization of our minimum-cut algorithm computes a minimum-cost subgraph in every Z2-homology class. We also prove that finding a minimum-cost subgraph homologous to a single input cycle is {NP}-hard.

Efficient construction of network topology to conserve energy in wireless ad hoc networks

Wireless ad hoc networks are usually composed of battery constraint devices, which make energy conservation a vital concern of their design. Reducing energy consumption has been addressed through different aspects till now. Topology Control (TC) is a well-known approach which tries to assign transmission ranges of nodes to optimize their energy utilization while keeping some network properties like connectivity. However, in current TC schemes, the transmission range of each node is mostly accounted as the exclusive estimator for its energy consumption, while ignoring the amount of data it sends or relays. In this paper, we redefine the problem of Topology Control regarding both transmission range and traffic load parameters. After proving the NP-hardness of the new problem, we mathematically formulate it as a mixed integer linear programming problem to find optimal solutions. Then, we introduce polynomial-time heuristic algorithms to practically solve the problem. During construction of network topology, we deliberately take into account the impact of the employed routing method on load of individual nodes. Finally, we show the advantages of our proposals through simulations.

Energy conserving movement-assisted deployment of ad hoc sensor networks

Sensor network deployment is very challenging due to hostile and unpredictable nature of usage environments. In this letter, we propose two methods for the self-deployment of mobile sensors. The first one is a randomized solution that provides both simplicity and applicability to different environments. Inspired by simulated annealing, it improves both speed and energy conservation of the deployment process. The other method is suggested for environments where sensors form a connected graph, initially. At the cost of this extra limitation, we gain considerable improvements.

FuFaIR: a Fuzzy Farsi Information Retrieval System

Persian (Farsi) is one of the languages of Middle East. There are significant amount of Persian documents available in digital form and even more are created every day. Therefore, there is a necessity to implement Information Retrieval System with high precision for this language. This paper discusses the design, implementation and testing of a Fuzzy retrieval system for Persian called FuFaIR. This system also supports Fuzzy quantifiers in its query language. Tests have been conducted using a standard Persian test corpus called Hamshari. The performance results obtained from FuFaIR are positive and they indicate that the FuFaIR could notably outperform well known industry systems such as the vector space model.

Homology flows, cohomology cuts

We describe the first algorithm to compute maximum flows in surface-embedded graphs in near-linear time. Specifically, given a graph embedded on a surface of genus

Joint range assignment and routing to conserve energy in wireless ad hoc networks

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All-Pairs Minimum Cuts in Near-Linear Time for Surface-Embedded Graphs.

, with two specified vertices

Tracing Compressed Curves in Triangulated Surfaces

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How to walk your dog in the mountains with no magic leash

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GAAM: an energy conservation method using code migration for ad hoc sensor networks

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