270,602 research outputs found
0-1 Integer Linear Programming with a Linear Number of Constraints
We give an exact algorithm for the 0-1 Integer Linear Programming problem
with a linear number of constraints that improves over exhaustive search by an
exponential factor. Specifically, our algorithm runs in time
where n is the number of variables and cn is the
number of constraints. The key idea for the algorithm is a reduction to the
Vector Domination problem and a new algorithm for that subproblem
Quantum Circuit Implementation and Resource Analysis of LBlock and LiCi
Due to Grover's algorithm, any exhaustive search attack of block ciphers can
achieve a quadratic speed-up. To implement Grover,s exhaustive search and
accurately estimate the required resources, one needs to implement the target
ciphers as quantum circuits. Recently, there has been increasing interest in
quantum circuits implementing lightweight ciphers. In this paper we present the
quantum implementations and resource estimates of the lightweight ciphers
LBlock and LiCi. We optimize the quantum circuit implementations in the number
of gates, required qubits and the circuit depth, and simulate the quantum
circuits on ProjectQ. Furthermore, based on the quantum implementations, we
analyze the resources required for exhaustive key search attacks of LBlock and
LiCi with Grover's algorithm. Finally, we compare the resources for
implementing LBlock and LiCi with those of other lightweight ciphers.Comment: 29 pages,21 figure
Applying Grover's algorithm to AES: quantum resource estimates
We present quantum circuits to implement an exhaustive key search for the
Advanced Encryption Standard (AES) and analyze the quantum resources required
to carry out such an attack. We consider the overall circuit size, the number
of qubits, and the circuit depth as measures for the cost of the presented
quantum algorithms. Throughout, we focus on Clifford gates as the
underlying fault-tolerant logical quantum gate set. In particular, for all
three variants of AES (key size 128, 192, and 256 bit) that are standardized in
FIPS-PUB 197, we establish precise bounds for the number of qubits and the
number of elementary logical quantum gates that are needed to implement
Grover's quantum algorithm to extract the key from a small number of AES
plaintext-ciphertext pairs.Comment: 13 pages, 3 figures, 5 tables; to appear in: Proceedings of the 7th
International Conference on Post-Quantum Cryptography (PQCrypto 2016
Anytime Subgroup Discovery in Numerical Domains with Guarantees
International audienceSubgroup discovery is the task of discovering patterns that accurately discriminate a class label from the others. Existing approaches can uncover such patterns either through an exhaustive or an approximate exploration of the pattern search space. However, an exhaustive exploration is generally unfeasible whereas approximate approaches do not provide guarantees bounding the error of the best pattern quality nor the exploration progression ("How far are we of an exhaustive search"). We design here an algorithm for mining numerical data with three key properties w.r.t. the state of the art: (i) It yields progressively interval patterns whose quality improves over time; (ii) It can be interrupted anytime and always gives a guarantee bounding the error on the top pattern quality and (iii) It always bounds a distance to the exhaustive exploration. After reporting experimentations showing the effectiveness of our method, we discuss its generalization to other kinds of patterns
Anytime Coalition Structure Generation with Worst Case Guarantees
Coalition formation is a key topic in multiagent systems. One would prefer a
coalition structure that maximizes the sum of the values of the coalitions, but
often the number of coalition structures is too large to allow exhaustive
search for the optimal one. But then, can the coalition structure found via a
partial search be guaranteed to be within a bound from optimum? We show that
none of the previous coalition structure generation algorithms can establish
any bound because they search fewer nodes than a threshold that we show
necessary for establishing a bound. We present an algorithm that establishes a
tight bound within this minimal amount of search, and show that any other
algorithm would have to search strictly more. The fraction of nodes needed to
be searched approaches zero as the number of agents grows. If additional time
remains, our anytime algorithm searches further, and establishes a
progressively lower tight bound. Surprisingly, just searching one more node
drops the bound in half. As desired, our algorithm lowers the bound rapidly
early on, and exhibits diminishing returns to computation. It also drastically
outperforms its obvious contenders. Finally, we show how to distribute the
desired search across self-interested manipulative agents
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