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Protection from predators is the main function of a fish school. Being in a school, fish detect danger faster and from a greater distance, and the distance between a school and a predator allows responding to its actions in a timely manner (collective protection). The presence of scout-fish in a school makes it possible to control the position and intentions of a predator (inspection behavior). The density of a school in case of danger, the quick and short bursts of individual fish and the defensive maneuvering of the entire school (f-maneuver, or fountain effect) disorientate a predator and reduce the success of its hunt. The larger the school, the faster and more accurately the fish perform defensive reactions, and the higher the protective function of the school. Vulnerability to predators depends on the behavior of schooling fish—individuals that leave a school even for a short time, show increased nervousness and motor activity, and fish that are phenotypically different from the homogeneous majority of the school become prey. Accessibility of schooling fish for predators depends on the illumination. Only lurking predators or predators capable of uniting and using collective attack tactics can overcome schooling defenses during direct attacks on pelagic fish in the daytime. Grouping of fish in a school reduces the risk of infection with some parasites. [ABSTRACT FROM AUTHOR]

Generalising the attack structure in argumentation frameworks (AFs) has been studied in different ways. Most prominently, the binary attack relation of Dung frameworks has been extended to the notion of collective attacks. The resulting formalism is often termed SETAFs. Among the generalisations of AFs, abstract dialectical frameworks (ADFs) allow for a systematic and flexible generalisation of AFs in which different kinds of logical relations, e.g. attack and support, among arguments can be represented. Restricting the logical relations among arguments leads to different subclasses of ADFs of interest. In this work, we consider so-called support-free ADFs that allow for all kinds of attacks but no support or other relations and SETADFs that embed SETAFs in the ADF setting. The aim of this paper is to shed light on the relation between these two different approaches. To this end, we investigate and compare the expressiveness of SETAFs and support-free ADFs under the lens of 3-valued semantics. Our results show that it is only the presence of unsatisfiable acceptance conditions in support-free ADFs that discriminates the two approaches. [ABSTRACT FROM AUTHOR]

Quantum Key Distribution is a secure method that implements cryptographic protocols. The applications of quantum key distribution technology have an important role: to enhance the security in communication systems. It is originally inspired by the physical concepts associated with quantum mechanics. It aims to enable a secure exchange of cryptographic keys between two parties through an unsecured quantum communication channel. This work proposes a secure half-duplex bidirectional quantum key distribution protocol. The security of the proposed protocol is proved against collective attacks by estimating the interception of any eavesdropper with high probability in both directions under the control of the two parties. A two-qubit state encodes two pieces of information; the first qubit represents the transmitted bit and the second qubit represents the basis used for measurement. The partial diffusion operator is used to encrypt the transmitted qubit state as an extra layer of security. The predefined symmetry transformations induced by unitary in conjunction with the asymmetrical two-qubit teleportation scheme retain the protocol's secrecy. Compared to the previous protocols, the proposed protocol has better performance on qubit efficiency. [ABSTRACT FROM AUTHOR]

Quantum Key Distribution is a secure method that implements cryptographic protocols. The applications of quantum key distribution technology have an important role: to enhance the security in communication systems. It is originally inspired by the physical concepts associated with quantum mechanics. It aims to enable a secure exchange of cryptographic keys between two parties through an unsecured quantum communication channel. This work proposes a secure half-duplex bidirectional quantum key distribution protocol. The security of the proposed protocol is proved against collective attacks by estimating the interception of any eavesdropper with high probability in both directions under the control of the two parties. A two-qubit state encodes two pieces of information; the first qubit represents the transmitted bit and the second qubit represents the basis used for measurement. The partial diffusion operator is used to encrypt the transmitted qubit state as an extra layer of security. The predefined symmetry transformations induced by unitary in conjunction with the asymmetrical two-qubit teleportation scheme retain the protocol’s secrecy. Compared to the previous protocols, the proposed protocol has better performance on qubit efficiency.

The problem of partitioning a quantum pure-state set into unambiguously discriminable subsets is investigated in this paper. We prove that the problem is decomposable into sub-problems of two-subset partitioning. A recursive algebro-geometric method based on Generalized Principal Component Analysis(GPCA) is proposed. When multiple feasible partitions exist, our method is able to return all of them by introducing Brill's equations. Through this method, the efficiency of a kind of collective photon-number-splitting(PNS) attack is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Based on a kind of multiparty quantum secret sharing schemes with Bell states, we propose a novel collective attack strategy in this paper. In our strategy, the group of in-attackers can obtain the entire secret information without introducing any error. More interestingly, a new multiparty quantum secret sharing scheme is proposed based on the 3-element phase shift operations. The scheme can resist not only the existing attacks, but also the cheating attack from the dishonest agent. Meanwhile, the scheme improves the efficiency of scheme by reducing the number of the eavesdropping detections and the computation complexity. [Copyright &y& Elsevier]