A Biordered Set Representation of Regular Semigroups by Yu B.J., Xu M.

By Yu B.J., Xu M.

Show description

Read or Download A Biordered Set Representation of Regular Semigroups PDF

Best symmetry and group books

The Locked Room and Other Stories

A tree choked with huge, immense spiders; curtains like a useless man's hair; an previous guy without center - those are a few of the issues that readers will observe in those terrifying brief tales. "Penguin Readers" is a chain of simplified novels, movie novelizations and unique titles that introduce scholars in any respect degrees to the pleasures of interpreting in English.

Luftwaffe Sturmgruppen

The 'storm soldiers' of the Luftwaffe, the elite Strumgruppen devices comprised the main seriously armed and armoured fighter interceptors ever produced by way of the Germans. Their position was once to spoil like a strong fist throughout the massed ranks of USAAF sunlight bombers. purely volunteers may perhaps serve with those elite devices, and every pilot used to be expert to shut with the enemy and interact him in tremendous short-range wrestle, attacking from front and the rear in tight arrowhead formations.

Additional resources for A Biordered Set Representation of Regular Semigroups

Example text

3 Security and efficiency requirements The main goal of the group key management is to assure that only authorized users are in the possession of the group key. As the group is dynamic, the group key must be changed accordingly, and this must be done securely. The security requirements for the group management are: • Forward secrecy (or forward access control): Impossibility of a former group member that has been excluded to gain access to future group keys and implicitly to future multicast group traffic.

Thus, the CAG is obtained from the diagraph of relation ≺ by eliminating all one length cycles, implied by the reflexive property, and all the arcs implied by the transitive property. The result is a directed, intransitive, acyclic, and non-reflexive graph, as shown in Figure 4-1. Since ≺ has a greatest element in rc, it can be shown that CAG has exactly one node, the rc, with in-degree zero. Moreover, it follows from the properties of ≺ and the construction of CAG that for any node in CAG, different than rc, there is at least one directed path from rc to that node.

The controller initiates all the sessions, generates and distributes the keys, maintains information about the categories, and accordingly adds and removes users and categories to and from the multicast group. Although the central controller can be a potential performance bottleneck, this architecture is more desirable in systems where one party must retain the control such as in multicast software delivery [HS00, Han01]. Moreover, methods of replication can be used to unload the controller. 36 CATEGORY-BASED GROUP KEY MANAGEMENT We assume that categories are excluded based on the accessibility relation and we formulate the requirement that is used in the design of our solution: • ∀ci , c j ∈ C : c j ∈ E ∧ ci ≺ c j → ci ∈ E ; • No coalition of users from excluded categories can gain access to future group keys.

Download PDF sample

Rated 4.03 of 5 – based on 26 votes