Venkatesh Srinivasan

Venkatesh Srinivasan
University of Victoria | UVIC · Department of Computer Science

PhD

About

119
Publications
10,262
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1,401
Citations

Publications

Publications (119)
Article
Full-text available
Authentication plays a critical role in the security of quantum key distribution (QKD) protocols. We propose using Polynomial Hash and its variants for authentication of variable length messages in QKD protocols. Since universal hashing is used not only for authentication in QKD but also in other steps in QKD like error correction and privacy ampli...
Article
Full-text available
Graphlet enumeration is a basic task in graph analysis with many applications. Thus it is important to be able to perform this task within a reasonable amount of time. However, this objective is challenging when the input graph is very large, with millions of nodes and edges. Known solutions are limited in terms of the scale of the graph that they...
Article
Full-text available
Truss decomposition is a popular notion of hierarchical dense substructures in graphs. In a nutshell, k-truss is the largest subgraph in which every edge is contained in at least k triangles. Truss decomposition aims to compute k-trusses for each possible value of k. There are many works that study truss decomposition in deterministic graphs. Howev...
Article
We consider misinformation propagating through a social network and study the problem of its prevention. The goal is to identify a set of $k$ users that need to be convinced to adopt a limiting campaign so as to minimize the number of people that end up adopting the misinformation. This work presents Reverse Prevention Sampling (RPS), an algorithm...
Preprint
A \emph{simple} $s,t$ path $P$ in a rectangular grid graph $\mathbb{G}$ is a Hamiltonian path from the top-left corner $s$ to the bottom-right corner $t$ such that each \emph{internal} subpath of $P$ with both endpoints $a$ and $b$ on the boundary of $\mathbb{G}$ has the minimum number of bends needed to travel from $a$ to $b$ (i.e., $0$, $1$, or $...
Chapter
We give a complete structure theorem for 1-complex s, t Hamiltonian paths in rectangular grid graphs. We use the structure theorem to design an algorithm to reconfigure one such path into any other in linear time, making a linear number of switch operations in grid cells.
Article
Full-text available
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for millions of deaths around the world. To help contribute to the understanding of crucial knowledge and to further generate new hypotheses relevant to SARS-CoV-2 and human protein interactions, we make use of the information abundant Biomine probabilistic database and...
Preprint
Full-text available
Mining dense subgraphs where vertices connect closely with each other is a common task when analyzing graphs. A very popular notion in subgraph analysis is core decomposition. Recently, Esfahani et al. presented a probabilistic core decomposition algorithm based on graph peeling and Central Limit Theorem (CLT) that is capable of handling very large...
Preprint
Full-text available
The SARS-CoV-2 coronavirus is responsible for millions of deaths around the world. To help contribute to the understanding of crucial knowledge and to further generate new hypotheses relevant to SARS-CoV-2 and human protein interactions, we make use of the information abundant Biomine probabilistic database and extend the experimentally identified...
Conference Paper
We study the following reconfiguration problem: given two s, t Hamiltonian paths connecting diagonally opposite corners s and t of a rectangular grid graph G, can we transform one to the other using only local operations in the grid cells? In this work, we introduce the notion of simples, t Hamiltonian paths, and give an algorithm to reconfigure su...
Conference Paper
Triangle counting is a major graph problem with several applications in social network analysis, anomaly detection, etc. One of the most popular triangle computational models considered is Edge Streaming in which the edges arrive in the form of a graph stream. We categorize the existing literature into two categories: Fixed Memory (FM) approach, an...
Conference Paper
Triangle enumeration is a fundamental task in graph data analysis with many applications. Recently, Park et al. proposed a distributed algorithm, PTE (Pre-partitioned Triangle Enumeration), that, unlike previous works, scales well using multiple high end machines and can handle very large real-world networks. This work presents a serverless impleme...
Preprint
In this paper, we first give explicit formulas for the number of solutions of unweighted linear congruences with distinct coordinates. Our main tools are properties of Ramanujan sums and of the discrete Fourier transform of arithmetic functions. Then, as an application, we derive an explicit formula for the number of codewords in the Varshamov--Ten...
Preprint
Universal hash functions, discovered by Carter and Wegman in 1979, are of great importance in computer science with many applications. MMH$^*$ is a well-known $\triangle$-universal hash function family, based on the evaluation of a dot product modulo a prime. In this paper, we introduce a generalization of MMH$^*$, that we call GMMH$^*$, using the...
Preprint
Let $\Z_n[i]$ be the ring of Gaussian integers modulo a positive integer $n$. Very recently, Camarero and Mart\'{i}nez [IEEE Trans. Inform. Theory, {\bf 62} (2016), 1183--1192], showed that for every prime number $p>5$ such that $p\equiv \pm 5 \pmod{12}$, the Cayley graph $\mathcal{G}_p=\textnormal{Cay}(\Z_p[i], S_2)$, where $S_2$ is the set of uni...
Preprint
A fundamental challenge in graph mining is the ever-increasing size of datasets. Graph summarization aims to find a compact representation resulting in faster algorithms and reduced storage needs. The flip side of graph summarization is the loss of utility which diminishes its usability. The key questions we address in this paper are: (1)How to sum...
Preprint
Full-text available
Finding dense components in graphs is of great importance in analyzing the structure of networks. Popular and computationally feasible frameworks for discovering dense subgraphs are core and truss decompositions. Recently, Sariy\"uce et al. introduced nucleus decomposition, a generalization which uses higher-order structures and can reveal interest...
Conference Paper
In this work, we consider misinformation propagating through a social network and study the problem of its prevention. In this problem, a "bad" campaign starts propagating from a set of seed nodes in the network and we use the notion of a limiting (or "good") campaign to counteract the effect of misinformation. The goal is to identify a set of k us...
Conference Paper
MapReduce is a widely used parallel computing paradigm for the big data realm on the scale of terabytes and higher. The introduction of minimal MapReduce algorithms promised efficiency in load balancing among participating machines by ensuring that partition skew (where some machines end up processing a significantly larger fraction of the input th...
Article
Stack Overflow is the most popular Q&A website among software developers. As a platform for knowledge sharing and acquisition, the questions posted on Stack Overflow usually contain a code snippet. Determining the programming language of a source code file has been considered in the research community; it has been shown that Machine Learning (ML) a...
Article
Recently, Grynkiewicz et al. [{\it Israel J. Math.} {\bf 193} (2013), 359--398], using tools from additive combinatorics and group theory, proved necessary and sufficient conditions under which the linear congruence $a_1x_1+\cdots +a_kx_k\equiv b \pmod{n}$, where $a_1,\ldots,a_k,b,n$ ($n\geq 1$) are arbitrary integers, has a solution $\langle x_1,\...
Conference Paper
Full-text available
Truss decomposition is popular for finding dense substructures in graphs. Discovering trusses in deterministic graphs has been widely discussed in the literature. However, with the intrinsic uncertainty in many networks such as social, biological, and communication networks, it is of great importance to study truss decomposition in a probabilistic...
Conference Paper
Full-text available
Core decomposition is a popular tool for analyzing the structure of network graphs. For probabilistic graphs the computation comes with several challenges and the state-of-the-art approach is not scalable to large graphs. One of the challenges is to compute tail probabilities of vertex degrees in probabilistic graphs. To address this we employ a sp...
Preprint
Full-text available
Determining the programming language of a source code file has been considered in the research community; it has been shown that Machine Learning (ML) and Natural Language Processing (NLP) algorithms can be effective in identifying the programming language of source code files. However, determining the programming language of a code snippet or a fe...
Preprint
Full-text available
Stack Overflow is the most popular Q&A website among software developers. As a platform for knowledge sharing and acquisition, the questions posted in Stack Overflow usually contain a code snippet. Stack Overflow relies on users to properly tag the programming language of a question and it simply assumes that the programming language of the snippet...
Article
Full-text available
In this paper, we first give explicit formulas for the number of solutions of unweighted linear congruences with distinct coordinates. Our main tools are properties of Ramanujan sums and of the discrete Fourier transform of arithmetic functions. Then, as an application, we derive an explicit formula for the number of codewords in the Varshamov–Tene...
Conference Paper
The analysis of characteristics of large-scale graphs has shown tremendous benefits in social networks, spam detection, epidemic disease control, analyzing software systems and so on. However, today, processing graph algorithms on massive datasets is not an easy task not only because of the large data volume, but also the complexity of the graph al...
Preprint
Full-text available
In this work, we consider misinformation propagating through a social network and study the problem of its prevention. In this problem, a "bad" campaign starts propagating from a set of seed nodes in the network and we use the notion of a limiting (or "good") campaign to counteract the effect of misinformation. The goal is then to identify a subset...
Article
Universal hashing, discovered by Carter and Wegman in 1979, has many important applications in computer science. MMH$^*$, which was shown to be $\Delta$-universal by Halevi and Krawczyk in 1997, is a well-known universal hash function family. We introduce a variant of MMH$^*$, that we call GRDH, where we use an arbitrary integer $n>1$ instead of pr...
Conference Paper
Often graph theory is used to model and analyze different behaviors of networks including social networks. Nowadays, social networks have become very popular and social network providers try to expand their networks by encouraging people to stay engaged and active. Studies show that engagement and activities of people in social networks influence e...
Article
The Markov Modulated Poisson Process (MMPP) has been extensively studied in random process theory and widely applied in various applications involving Poisson arrivals whose rate varies following a Markov process. Despite the rich literature on MMPP, very little is known on its intricate temporal dependence structure. No exact solution is available...
Article
We consider the problem of assigning radii to a given set of points in the plane, such that the resulting set of disks is connected, and the sum of radii is minimized. We prove that the problem is NP-hard in planar weighted graphs if there are upper bounds on the radii and sketch a similar proof for planar point sets. For the case when there are no...
Article
In this paper, using properties of Ramanujan sums and of the discrete Fourier transform of arithmetic functions, we give an explicit formula for the number of solutions of the linear congruence $a_1x_1+\cdots +a_kx_k\equiv b \pmod{n}$, with $\gcd(x_i,n)=t_i$ ($1\leq i\leq k$), where $a_1,t_1,\ldots,a_k,t_k, b,n$ ($n\geq 1$) are arbitrary integers....
Article
The minimum feedback arc set problem is an NP-hard problem on graphs that seeks a minimum set of arcs which, when removed from the graph, leave it acyclic. In this work, we investigate several approximations for computing a minimum feedback arc set with the goal of comparing the quality of the solutions and the running times. Our investigation is m...
Conference Paper
Full-text available
Universal hashing, discovered by Carter and Weg-man in 1979, has many important applications in computer science. As a well known family, one can mention MMH * which was shown to be-universal by Halevi and Krawczyk in 1997. In this paper, we first introduce a variant of MMH * that we call GRDH. Then via a novel approach, namely, connecting the univ...
Article
Let $b,n\in \mathbb{Z}$, $n\geq 1$, and ${\cal D}_1, \ldots, {\cal D}_{\tau(n)}$ be all positive divisors of $n$. For $1\leq l \leq \tau(n)$, define ${\cal C}_l:=\lbrace 1 \leqslant x\leqslant n \; : \; (x,n)={\cal D}_l\rbrace$. In this paper, by combining ideas from the finite Fourier transform of arithmetic functions and Ramanujan sums, we give a...
Conference Paper
The weighted bipartite B-matching (WBM) problem models a host of data management applications, ranging from recommender systems to Internet advertising and e-commerce. Many of these applications, however, demand versatile assignment constraints, which WBM is weak at modelling. In this paper, we investigate powerful generalisations of WBM. We first...
Conference Paper
Portable smart devices have become prevalent and are used for ubiquitous access to the Internet in our daily life. Taking advantage of this trend, brick-and-mortar retailers have been increasingly deploying free Wi-Fi hotspots to provide easy Internet access for their customers. This opens the opportunity for retailers to collect customer informati...
Article
In this paper, using properties of Ramanujan sums and of the discrete Fourier transform of arithmetic functions, we give an explicit formula for the number of solutions of the linear congruence , with ( ), where ( ) are arbitrary integers. As a consequence, we derive necessary and sufficient conditions under which the above restricted linear congru...
Article
Let Z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> [i] be the ring of Gaussian integers modulo a positive integer n. Very recently, Camarero and Martinez et al. showed that for every prime number p > 5 such that p ≡ ±5 (mod 12), the Cayley graph ς <sub xmlns:mml="http://www.w3.org/1998/Math/...
Article
Full-text available
We study connectivity relations among points, where the precise location of each input point lies in a region of uncertainty. We distinguish two fundamental scenarios under which uncertainty arises. In the favorable Best-Case Uncertainty, each input point can be chosen from a given set to yield the best possible objective value. In the unfavorable...
Conference Paper
In ICDE'12, Afrati, Das Sarma, Menestrina, Parameswaran and Ullman proposed similarity join algorithms for MapReduce. In this paper, we evaluate and extend their research, testing their proposed algorithms using edit distance and Jaccard similarity. We provide details of adaptations needed to implement their algorithms based on these similarity mea...
Article
The weighted bipartite b-matching problem (WBM) plays a significant role in many real-world applications, including resource allocation, scheduling, Internet advertising, and E-commerce. WBM has been widely studied and efficient matching algorithms are well known. In this work, we study a novel variant of WBM, called conflict-aware WBM (CA-WBM), wh...
Article
Universal hash functions, discovered by Carter and Wegman in 1979, are of great importance in computer science with many applications. MMH* is a well-known △-universal hash function family, based on the evaluation of a dot product modulo a prime. In this paper, we introduce a generalization of MMH*, that we call GMMH*, using the same construction a...
Article
Full-text available
Graphs embedded into surfaces have many important applications, in particular, in combinatorics, geometry, and physics. For example, ribbon graphs and their counting is of great interest in string theory and quantum field theory (QFT). Recently, Koch, Ramgoolam, and Wen [Nuclear Phys.B 870 (2013), 530–581] gave a refined formula for counting ribbon...
Conference Paper
We propose generic constructions of public-key encryption schemes, satisfying key-dependent message (KDM) security for projections and different forms of key-leakage resilience, from CPA-secure private-key encryption schemes with two main abstract properties: (1) a form of (additive) homomorphism with respect to both plaintexts and randomness, and...
Chapter
Studying the topology of a network is critical to inferring underlying dynamics such as tolerance to failure, group behavior and spreading patterns. k-core decomposition is a well-established metric which partitions a graph into layers from external to more central vertices. In this paper we aim to explore whether k-core decomposition of large netw...
Article
Studying the topology of a network is critical to inferring underlying dynamics such as tolerance to failure, group behavior and spreading patterns. k-core decomposition is a well-established metric which partitions a graph into layers from external to more central vertices. In this paper we aim to explore whether k-core decomposition of large netw...
Article
We report experimental results for the MapReduce algorithms proposed by Afrati, Das Sarma, Menestrina, Parameswaran and Ullman in ICDE'12 to compute fuzzy joins of binary strings using Hamming Distance. Their algorithms come with complete theoretical analysis, however, no experimental evaluation is provided. They argue that there is a tradeoff betw...
Article
In an emerging trend, more and more Internet users search for information from Community Question and Answer (CQA) websites, as interactive communication in such websites provides users with a rare feeling of trust. More often than not, end users look for instant help when they browse the CQA websites for the best answers. Hence, it is imperative t...
Article
Full-text available
Universal hashing, discovered by Carter and Wegman in 1979, has many applications in computer science, for example, in cryptography, randomized algorithms, dictionary data structures etc. The following family is a famous construction: Let $p$ be a prime and $k$ be a positive integer. Define \begin{align*} \text{MMH}^*:=\lbrace g_{\mathbf{x}} \; : \...
Article
We study the problem of anonymizing data by column suppression. Meyerson and Williams showed that this problem is NP-hard for . The complexity of this problem for remained open. In this note, we show that 2-anonymizing data by suppressing the minimum number of columns is also NP-hard. In fact, we prove a stronger claim that this problem is NP-hard...
Chapter
We initiate a systematic study to help distinguish a special group of online users, called hidden paid posters, or termed “Internet water army” in China, from the legitimate ones. On the Internet, the paid posters represent a new type of online job opportunities. They get paid for posting comments or articles on different online communities and web...
Article
In this work, we study the problem of clearing contamination spreading through a large network where we model the problem as a graph searching game. The problem can be summarized as constructing a search strategy that will leave the graph clear of any contamination at the end of the searching process in as few steps as possible. We show that this p...
Preprint
The majority of recommender systems are designed to recommend items (such as movies and products) to users. We focus on the problem of recommending buyers to sellers which comes with new challenges: (1) constraints on the number of recommendations buyers are part of before they become overwhelmed, (2) constraints on the number of recommendations se...
Article
We study three-way joins on MapReduce. Joins are very useful in a multitude of applications from data integration and traversing social networks, to mining graphs and automata-based constructions. However, joins are expensive, even for moderate data sets; we need efficient algorithms to perform distributed computation of joins using clusters of man...
Conference Paper
Since the Netflix Prize competition, latent factor models (LFMs) have become the comparison "staples" for many of the recent recommender methods. The performance improvement of LFMs over baseline approaches, however, hovers at only low percentage numbers. Therefore, it is time for a better understanding of their real power beyond the overall RMSE (...
Article
Regret minimizing sets are a recent approach to representing a dataset D by a small subset R of size r of representative data points. The set R is chosen such that executing any top-1 query on R rather than D is minimally perceptible to any user. However, such a subset R may not exist, even for modest sizes, r. In this paper, we introduce the relax...
Conference Paper
We consider the recently introduced monochromatic reverse top−k query which asks for, given a (possibly new) tuple q and a dataset \(\mathcal{D}\), all possible top−k queries on \(\mathcal{D}\cup\{q\}\) for which q is in the result. Towards this problem, we introduce the first query-agnostic approach, which leads to an efficient index. We present t...
Article
Full-text available
For a graph-based representation of a social network, the identity of participants can be uniquely determined if an adversary has background structural knowledge about the graph. We focus on degree-based attacks, wherein the adversary knows the degrees of particular target vertices and we aim to protect the anonymity of participants through k-anony...
Conference Paper
Full-text available
In an emerging trend, more and more Internet users search for information from Community Question and Answer (CQA) websites, as interactive communication in such websites provides users with a rare feeling of trust. More often than not, end users look for instant help when they browse the CQA websites for the best answers. Hence, it is imperative t...