OALib Journal期刊

ISSN: 2333-9721



匹配条件: “Khot Sachin” ,找到相关结果约670条。
Optimize Security solution for mobile agent security: A Review
Sachin Upadhye,P.G.Khot
International Journal of Engineering and Computer Science , 2013,
Abstract: The field of agents has many diverse researchers, approaches and ideas, which has helped to create one of the more dynamic research areas in recent years. Mobile agents are enjoying a lot of popularity and are destined to influence research in distributed systems for the years to come. Thus far, technology has been instrumental in disseminating new design paradigms where application components are not permanently bound to the hosts where they execute. Mobile agents are gaining in complexity as they evolve and are now widely used in e-commerce. All phases of a business transaction, such as negotiating and signing contracts can be done using mobile agents. In this paper, we provided a brief introduction to the recent researches & developments associated with the field of mobile agents, highlighting various security threats, also touching the weakest hot-spots of the field which need to be nurtured.This paper also focuses on the optimization of computation cost for agent platform, which appears due to complex security operations. Traditionally, a security manager is integrated within an agent platform, which performs these operations for every mobile agent visiting the platform. To reduce the security costs at the agent platform, a detached security manager is used, which performs complex security operations on behalf of multiple agent platforms.The paper is structured as follows. Section 1 Introduction to multi agent system and security. Section 2 briefly describes the characteristics of agents and Security Services. In section 3 we will discuss some security threats and countermeasures and in last section describes some recent research aimed at enhancing the security of mobile agent systems
Study of sunscreen activity of aqueous, methanol and acetone extracts of leaves of Pongamia pinnata (L.) pierre, fabaceae
Shenoy Priyank,Khot Sachin,Chavan Manisha,Takawale Jagruti
International Journal of Green Pharmacy , 2010,
Abstract: The present research work evaluates the photoabsorptive property of different extracts of the leaves of Pongamia pinnata (L.) Pierre, Fabaceae, in the ultraviolet region (200-400 nm) and its comparison with a well-established standard sunscreen drug, p-aminobenzoic acid (PABA). The shade-dried leaves of the plant were extracted in Soxhlet apparatus using three different solvents, i.e., water, methanol and acetone. The extracts were concentrated by evaporation of the solvent and finally dried to get dry extracts. Then, 20 mg of the dry extracts was dissolved in the respective solvents and their absorption spectra were measured using UV-visible spectrophotometer. Absorbance of different concentrations of the extracts, i.e., 5, 10, 15 and 20 mg/100 ml was read at their respective wavelengths (λmax ) of maximum absorption. The aqueous and methanol extracts were found to be highly effective in the UVB and moderately effective in the UVA region. Acetone extract was found to greatly absorb exclusively in the UVA region. The known standard drug PABA showed its protective action in the UVB and UVC regions with least effectiveness in the UVA region. The extracts of the leaves of the plant under study showed extremely good absorbance throughout the UV region including UVA region. The P. pinnata extract can be used to formulate highly effective sunscreen preparations as it will enhance and effectively contribute to the UV absorbing properties of a conventional sunscreen. It will also help in broadening the UV protection ability of the sunscreens along with the greatest advantage of avoiding the adverse and undesired effects of synthetic sunscreen compounds.
Indian Streams Research Journal , 2013,
Abstract: The budget is the most important factor in management accounting. It is for planning and its successful implementation. The budget refers to a statement showing the quantities and monetary values, and indicating the future policy to be perused by organization. In short, budget is an estimate of the future needs calculate for a definite period. It is also defined as “a blue-print of a projected plan of action of a business or Bank for a definite period of time.” It is considered as the management instrument of planning, organizing, Co-coordinating & control. Budgetary control is the requirement of Bharat co-operative urban bank Ltd. The study is mainly focused on the budgetary control of the co-operative bank. It overviewed the Receipts & Expenditure of Co-operative Bank. Budgetary control system is the very essence of financial control.
Nonembeddability theorems via Fourier analysis
Subhash Khot,Assaf Naor
Mathematics , 2005,
Abstract: Various new nonembeddability results (mainly into $L_1$) are proved via Fourier analysis. In particular, it is shown that the Edit Distance on $\{0,1\}^d$ has $L_1$ distortion $(\log d)^{\frac12-o(1)}$. We also give new lower bounds on the $L_1$ distortion of flat tori, quotients of the discrete hypercube under group actions, and the transportation cost (Earthmover) metric.
Sharp kernel clustering algorithms and their associated Grothendieck inequalities
Subhash Khot,Assaf Naor
Computer Science , 2009,
Abstract: In the kernel clustering problem we are given a (large) $n\times n$ symmetric positive semidefinite matrix $A=(a_{ij})$ with $\sum_{i=1}^n\sum_{j=1}^n a_{ij}=0$ and a (small) $k\times k$ symmetric positive semidefinite matrix $B=(b_{ij})$. The goal is to find a partition $\{S_1,...,S_k\}$ of $\{1,... n\}$ which maximizes $ \sum_{i=1}^k\sum_{j=1}^k (\sum_{(p,q)\in S_i\times S_j}a_{pq})b_{ij}$. We design a polynomial time approximation algorithm that achieves an approximation ratio of $\frac{R(B)^2}{C(B)}$, where $R(B)$ and $C(B)$ are geometric parameters that depend only on the matrix $B$, defined as follows: if $b_{ij} = < v_i, v_j>$ is the Gram matrix representation of $B$ for some $v_1,...,v_k\in \R^k$ then $R(B)$ is the minimum radius of a Euclidean ball containing the points $\{v_1, ..., v_k\}$. The parameter $C(B)$ is defined as the maximum over all measurable partitions $\{A_1,...,A_k\}$ of $\R^{k-1}$ of the quantity $\sum_{i=1}^k\sum_{j=1}^k b_{ij}< z_i,z_j>$, where for $i\in \{1,...,k\}$ the vector $z_i\in \R^{k-1}$ is the Gaussian moment of $A_i$, i.e., $z_i=\frac{1}{(2\pi)^{(k-1)/2}}\int_{A_i}xe^{-\|x\|_2^2/2}dx$. We also show that for every $\eps > 0$, achieving an approximation guarantee of $(1-\e)\frac{R(B)^2}{C(B)}$ is Unique Games hard.
Grothendieck-type inequalities in combinatorial optimization
Subhash Khot,Assaf Naor
Computer Science , 2011,
Abstract: We survey connections of the Grothendieck inequality and its variants to combinatorial optimization and computational complexity.
Hardness of Finding Independent Sets in 2-Colorable and Almost 2-Colorable Hypergraphs
Subhash Khot,Rishi Saket
Computer Science , 2013,
Abstract: This work studies the hardness of finding independent sets in hypergraphs which are either 2-colorable or are almost 2-colorable, i.e. can be 2-colored after removing a small fraction of vertices and the incident hyperedges. To be precise, say that a hypergraph is (1-eps)-almost 2-colorable if removing an eps fraction of its vertices and all hyperedges incident on them makes the remaining hypergraph 2-colorable. In particular we prove the following results. For an arbitrarily small constant gamma > 0, there is a constant xi > 0, such that, given a 4-uniform hypergraph on n vertices which is (1 - eps)-almost 2-colorable for eps = 2^{-(log n)^xi}, it is quasi-NP-hard to find an independent set of n/(2^{(log n)^{1-gamma}}) vertices. For any constants eps, delta > 0, given as input a 3-uniform hypergraph on $n$ vertices which is (1-eps)-almost 2-colorable, it is NP-hard to find an independent set of delta n vertices. Assuming the d-to-1 Games Conjecture the following holds. For any constant delta > 0, given a 2-colorable 3-uniform hypergraph on n vertices, it is NP-hard to find an independent set of delta n vertices. The hardness result on independent set in almost 2-colorable 3-uniform hypergraphs was earlier known only assuming the Unique Games Conjecture. In this work we prove the result unconditionally. For independent sets in 2-colorable 3-uniform hypergaphs we prove the first strong hardness result, albeit assuming the d-to-1 Games Conjecture. Our result on almost 2-colorable 4-uniform hypergraphs gives the first nearly polynomial hardness factor for independent set in hypergraphs which are (almost) colorable with constantly many colors. It partially bridges the gap between the previous best lower bound of poly(log n) and the algorithmic upper bounds of n^{Omega(1)}.
A Characterization of Approximation Resistance for Even $k$-Partite CSPs
Per Austrin,Subhash Khot
Computer Science , 2013,
Abstract: A constraint satisfaction problem (CSP) is said to be \emph{approximation resistant} if it is hard to approximate better than the trivial algorithm which picks a uniformly random assignment. Assuming the Unique Games Conjecture, we give a characterization of approximation resistance for $k$-partite CSPs defined by an even predicate.
A Simple Deterministic Reduction for the Gap Minimum Distance of Code Problem
Per Austrin,Subhash Khot
Computer Science , 2010,
Abstract: We present a simple deterministic gap-preserving reduction from SAT to the Minimum Distance of Code Problem over $\F_2$. We also show how to extend the reduction to work over any finite field. Previously a randomized reduction was known due to Dumer, Micciancio, and Sudan, which was recently derandomized by Cheng and Wan. These reductions rely on highly non-trivial coding theoretic constructions whereas our reduction is elementary. As an additional feature, our reduction gives a constant factor hardness even for asymptotically good codes, i.e., having constant rate and relative distance. Previously it was not known how to achieve deterministic reductions for such codes.
Approximate kernel clustering
Subhash Khot,Assaf Naor
Computer Science , 2008,
Abstract: In the kernel clustering problem we are given a large $n\times n$ positive semi-definite matrix $A=(a_{ij})$ with $\sum_{i,j=1}^na_{ij}=0$ and a small $k\times k$ positive semi-definite matrix $B=(b_{ij})$. The goal is to find a partition $S_1,...,S_k$ of $\{1,... n\}$ which maximizes the quantity $$ \sum_{i,j=1}^k (\sum_{(i,j)\in S_i\times S_j}a_{ij})b_{ij}. $$ We study the computational complexity of this generic clustering problem which originates in the theory of machine learning. We design a constant factor polynomial time approximation algorithm for this problem, answering a question posed by Song, Smola, Gretton and Borgwardt. In some cases we manage to compute the sharp approximation threshold for this problem assuming the Unique Games Conjecture (UGC). In particular, when $B$ is the $3\times 3$ identity matrix the UGC hardness threshold of this problem is exactly $\frac{16\pi}{27}$. We present and study a geometric conjecture of independent interest which we show would imply that the UGC threshold when $B$ is the $k\times k$ identity matrix is $\frac{8\pi}{9}(1-\frac{1}{k})$ for every $k\ge 3$.

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