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15th International Workshop on Combinatorial Image Analysis, IWCIA 2012

作者： Dutt, Mousumi Biswas, Arindam Bhowmick, Partha Bhattacharya, Bhargab B. Department of Information Technology Bengal Engineering and Science University Shibpur Howrah India Department of Computer Science and Engineering Indian Institute of Technology Kharagpur India Advanced Computing and Microelectronics Unit Indian Statistical Institute Kolkata India

ISBN: (纸本)9783642347313

Shortest path algorithms are finding interesting applications in recent times in various emerging areas of image analysis and computer vision. Such algorithms are designed to solve shortest path problems with variegated need-based constraints. We present here an efficient combinatorial algorithm to find a/the shortest isothetic path (SIP) between two grid points in a digital object such that the SIP lies entirely inside the object. The algorithm first obtains the inner isothetic cover (simple and without holes) of the object and then applies certain combinatorial rules to construct the SIP and its constituent monotone sub-paths. For a given grid size, the entire algorithm runs in O(n logn) time, n being the number of grid points on the border of the cover. Experimental results show the effectiveness of the algorithm and its further prospects in shape analysis. © 2012 Springer-Verlag.

关键词： Graph theory

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Distributed algorithm for traffic dissemination in manhattan networks with optimal routing-time 17

Distributed algorithm for traffic dissemination in manhattan...

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32nd Annual ACM Symposium on Applied computing, SAC 2017

作者： Sarma, Sayan Sen Sinha, Koushik Chakraborty, Goutam Sinha, Bhabani P. Advanced Computing and Microelectronics Unit Indian Statistical Institute Kolkata India Department of Computer Science Southern Illinois University Carbondale United States Department of Software and Information Science Iwate Prefectural University Iwate Ken Japan

ISBN: (纸本)9781450344869

We consider the problem of trafic routing in a road network in the event of a disaster, when there is a surge in vehicle movement from dense residential areas to designated safeshelters. We address the problem with multiple sources and a fixed sink in a κ × κ Manhattan grid road network to find a trafic distribution over the network such that the average time of travel from sources to sink is minimized. We consider queuing delay at each grid point of the Manhattan network when multiple grid points can become potential sources of new trafic generation, and then propose an optimal trafic distribution algorithm to minimize the total queuing delay of all vehicles to reach the given destination point. We then extend our technique to consider variable link delay (as a function of the volume of trafic ow through a link) along the links of the network. 2017 ACM.

关键词： Roads and streets

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An efficient approach for load balancing in vehicular ad-hoc networks

An efficient approach for load balancing in vehicular ad-hoc...

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2016 IEEE International Conference on advanced Networks and Telecommunications Systems, ANTS 2016

作者： Agarwal, Shubham Das, Avirup Das, Nabanita Department of Electrical and Electronics Engineering Manipal Institute of Technology Manipal University Manipal India Institute of Radio Physics and Electronics University of Calcutta Kolkata India Advanced Computing and Microelectronics Unit Indian Statistical Institute Kolkata India

ISBN: (纸本)9781509021932

With the rapid increase in vehicular traffic in urban areas, optimal use of available resources is necessary to minimize the cost while maintaining the safety, and the quality of service. For this purpose, Vehicular Ad hoc Networks (VANETs) are emerging, connecting vehicles with static road side units (RSUs) serving as a backbone. For energy efficiency, vehicles may upload data to the nearest RSU by multi-hop routing via shortest paths. But it drains the energy of the nodes nearer to the RSU faster leading to frequent recharging of batteries. For cost-efficient design and longer battery life, both optimal placement of RSUs and uniform power dissipation of nodes are necessary in VANETs. In this paper, a novel approach of load balanced routing is proposed to improve the network stability and battery lifetime in individual nodes. Assuming variable energy levels of transmission in each vehicle, our analysis establishes some upper bounds on the separation of two consecutive RSUs for nearly load balanced routing. The problem has been defined for linear network with uniform distribution of vehicles over 1-D road. Simulation studies show that the proposed scheme enhances the network performance significantly in terms of energy usage, network load and average packet delay. © 2016 IEEE.

关键词： Vehicular ad hoc networks

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Comment on "Quantum key agreement protocol"

arXiv

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arXiv 2020年

作者： Das, Nayana Majumdar, Ritajit Applied Statistics Unit Indian Statistical Institute India Advanced Computing & Microelectronics Unit Indian Statistical Institute India

The first two party Quantum Key Agreement (QKA) protocol, based on quantum teleportation, was proposed by Zhou et al. (Electronics Letters 40.18 (2004): 1149-1150). In this protocol, to obtain the key bit string, one of the parties use a device to obtain inner product of two quantum states, one being unknown, and the other one performs Bell measurement. However, in this article, we show that it is not possible to obtain a device that would output the inner product of two qubits even when only one of the qubit is unknown. This is so because existence of such device would imply perfectly distinguishing among four different states in a two-dimensional vector space. This is not permissible in quantum mechanics. Furthermore, we argue that existence of such a device would also imply violation of the "No Signalling Theorem" as well. Finally, we also comment that this protocol is not a valid key agreement protocol at all. Copyright © 2020, The Authors. All rights reserved.

关键词： Vector spaces

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Depth optimized ansatz circuit in QAOA for Max-Cut

arXiv

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arXiv 2021年

作者： Majumdar, Ritajit Bhoumik, Debasmita Madan, Dhiraj Vinayagamurthy, Dhinakaran Raghunathan, Shesha Sur-Kolay, Susmita Advanced Computing & Microelectronics Unit Indian Statistical Institute IBM Research India IBM Systems India

While a Quantum Approximate Optimization Algorithm (QAOA) is intended to provide a quantum advantage in finding approximate solutions to combinatorial optimization problems, noise in the system is a hurdle in exploiting its full potential. Several error mitigation techniques have been studied to lessen the effect of noise on this algorithm. Recently, Majumdar et al. proposed a Depth First Search (DFS) based method to reduce n-1 CNOT gates in the ansatz design of QAOA for finding Max-Cut in a graph G = (V;E), jV j = n. However, this method tends to increase the depth of the circuit, making it more prone to relaxation error. The depth of the circuit is proportional to the height of the DFS tree, which can be n-1 in the worst case. In this paper, we propose an O(Δ · n2) greedy heuristic algorithm, where Δ is the maximum degree of the graph, that finds a spanning tree of lower height, thus reducing the overall depth of the circuit while still retaining the n-1 reduction in the number of CNOT gates needed in the ansatz. We numerically show that this algorithm achieves 10 times increase in the probability of success for each iteration of QAOA for Max-Cut. We further show that although the average depth of the circuit produced by this heuristic algorithm still grows linearly with n, our algorithm reduces the slope of the linear increase from 1 to 0:11. © 2021, CC BY.

关键词： Heuristic algorithms

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Coverage Area Maximization by Heterogeneous Sensor Nodes With Minimum Displacement in Mobile Networks

Coverage Area Maximization by Heterogeneous Sensor Nodes Wit...

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IEEE International Conference on advanced Networks and Telecommuncations Systems

作者： Dibakar Saha Avirup Das Advanced Computing and Microelectronics Unit Indian Statistical Institute Department of Radio physics and Electronics University of Calcutta

ISBN: (纸本)9781509002948

Given a random deployment of heterogeneous mobile nodes having different sensing ranges, this paper addresses the problem of covering a region using minimum number of nodes with minimum displacement. We propose an energy-efficient and light-weight self-organized distributed greedy heuristic to maximize area coverage such that the amount of computation, rounds of communication, and the distance traversed by a node, can be reduced utilizing minimal number of nodes. Extensive simulation studies on random deployment of nodes with sufficient node density over a 2-D area, show that our proposed technique results hole free area coverage with small number of nodes with minimum possible displacement, both in turn help to prolong the network lifetime.

关键词： Area coverage Mobile networks Sensing range Connectedness Network lifetime

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A Multi-Arm-Bandit Based Resource Block Allocation in RIS Assisted Wireless Network

A Multi-Arm-Bandit Based Resource Block Allocation in RIS As...

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IEEE International Symposium on Network computing and Applications

作者： Souvik Deb Shankar Kumar Ghosh Sasthi C. Ghosh Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata India Presidency University Bangalore India

ISBN: (纸本)9781665495516

Designing resource block (RB) allocation mechanism for reconfigurable intelligent surface (RIS) assisted wireless networks is quite limited in the preceding literature. In RI S assisted environment, a user equipment (UE) receives throughput through two channels: firstly, through the direct channel from base station (BS) to UE; secondly, through the indirect channel from BS to UE via the RIS. The existing RB allocation mechanism considers only the direct channel conditions. However, in RIS assisted environment, RB selection based on only direct channel condition may not be the optimal one. This is because, a distant UE can achieve a high throughput through the indirect channel even if the direct channel condition is not good. In this work, first, we formulate the RB allocation problem in RIS assisted environment as a multi arm bandit (MAB) problem. Then based on the MAB formulation, we develop a two-phase $\epsilon$ -greedy algorithm which explicitly considers the throughput achievable through the indirect channel while selecting RBs. In exploitation phase, it selects the RB providing maximum reward with a probability $1-\epsilon$ . In exploration phase, any available RB is selected randomly with a probability $\epsilon$ . Finally, through extensive system level simulations, we have shown that our proposed algorithm performs better than an existing proportional fairness based RB allocation mechanism in terms of call dropping probability and system throughput.

关键词： Base stations Wireless networks Reconfigurable intelligent surfaces Throughput Resource management

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A synoptic study on fault testing in reversible and quantum circuits 1st

A synoptic study on fault testing in reversible and quantum ...

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1st International Conference on Algorithms and Applications, ALAP 2018

作者： Dey, Ramyadeep Bandyopadhyay, Paramita Chandra, Somenath Majumdar, Ritajit Department of Computer Science & Engineering B. P. Poddar Institute of Management & Technology Maulana Abul Kalam Azad University of Technology Kolkata India Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata India

ISBN: (纸本)9789811081019

Reversible computation, whose special class is quantum computation, arises from the desire to reduce power dissipation, which can be zero under ideal physical circumstances. Nowadays, error correction and fault testing are of utmost importance for the physical implementation of reversible and quantum circuits in a noisy environment. In this paper, we review various fault models in reversible and quantum circuits. In classical reversible circuits, we review (i) test pattern generation for Single Missing Gate Fault (SMGF), Partial Missing Gate Fault (PMGF), and Multiple Missing Gate Fault (MMGF) models and (ii) show that Universal Test Set (UTS) can be used to detect any of these faults. However, classical fault models do not capture all the logical failures found in quantum circuits. In quantum circuits, we review (i) depolarizing faults, initialization inaccuracy and measurement inaccuracy, and (ii) give some remedial strategies to deal with these fault models. Finally, we show that for a special class of quantum operators, detection of SMGF is sufficient to detect fault due to multiple occurrences of the gate also. Further, we argue with an example that it may not be possible to generate test patterns to detect any arbitrary SMGF in a quantum circuit. © Springer Nature Singapore Pte Ltd. 2018.

关键词： Error correction

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Optimized QAOA ansatz circuit design for two-body Hamiltonian problems

Optimized QAOA ansatz circuit design for two-body Hamiltonia...

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International Conference on VLSI Design

作者： Ritajit Majumdar Dhiraj Madan Debasmita Bhoumik Dhinakaran Vinayagamurthy Shesha Raghunathan Susmita Sur-Kolay IBM Quantum IBM India Research Lab Advanced Computing & Microelectronics Unit Indian Statistical Institute

Quantum Approximate Optimization Algorithm (QAOA) is a prospective candidate for providing quantum advantage in finding approximate solutions to optimization problems using near-term quantum devices. In this paper, the goal is to reduce the number of CNOT gates and the depth of quantum ansatz circuits for QAOA. First, we present a generalized QAOA formulation for any Hamiltonian that involves upto two-body interactions, as a graph. The circuit realization of the depth-p QAOA requires $2mp$ CNOT gates where the graph for the Hamiltonian has n vertices and m edges. Presently, a CNOT gate is one of the primary sources of error. We propose a graph-theoretic algorithm which can eliminate $n-1$ CNOTs from the QAOA ansatz while retaining functional equivalence with the original circuit. This improves upon previously proposed Depth First Search (DFS) method by restricting the increase in depth of the circuit, which was a drawback of the method, by $\simeq 84.8\%$ for Erdős-Renyi graphs. Finally, if the underlying connectivity (hardware coupling map) and the initial qubit placement for a hardware are known, then we present how to extend the greedy heuristic method in order to obtain a functionally equivalent circuit with $\simeq 5\%$; fewer SWAP gates for Erdős-Renyi graphs.

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Bottleneck bichromatic full steiner trees 29

Bottleneck bichromatic full steiner trees

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29th Canadian Conference on Computational Geometry, CCCG 2017

作者： Karim Abu-Affash, A. Bhore, Sujoy Carmi, Paz Chakraborty, Dibyayan Software Engineering Department Shamoon College of Engineering Beer-Sheva84100 Israel Department of Computer Science Ben-Gurion University Beer-Sheva84105 Israel Advanced Computing and Microelectronics Unit Indian Statistical Institute Kolkata India

Given two sets of points in the plane, Q of n (terminal) points and S of m (Steiner) points, where each of Q and S contains bichromatic points (red and blue points), a full bichromatic Steiner tree is a Steiner tree in which all points of Q are leaves and each edge of the tree is bichromatic (i.e., connects a red and a blue point). In the bottleneck bichromatic full Steiner tree (BBFST) problem, the goal is to compute a bichromatic full Steiner tree T, such that the length of the longest edge in T is minimized. In k-BBFST problem, the goal is to find a bichromatic full Steiner tree T with at most k ≤ m Steiner points from S, such that the length of the longest edge in T is minimized. In this paper, we present an O((n + m) log m) time algorithm that solves the BBFST problem. Moreover, we show that k-BBFST problem is NP-hard and we give a polynomial-time 9-approximation algorithm for the problem. Compilation copyright © 2017 Michiel Smid Copyright of individual papers retained by *** right reserved.

关键词： Polynomial approximation

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