Łukasz Maśko

Expressing attack-defence trees in a multiagent setting allows for studying a new aspect of security scenarios, namely, how the number of agents and their task assignment impact the performance, e.g. , attack time, of strategies executed by opposing coalitions. Optimal scheduling of agents' actions, a nontrivial problem, is thus vital. We discuss associated caveats and propose an algorithm that synthesizes such an assignment, targeting minimal attack time and using the minimal number of agents for a given attack-defence tree. We also investigate an alternative approach for the same problem using rewriting logic, starting with a simple and elegant declarative model, whose correctness (in terms of schedule's optimality) is self-evident. We then refine this specification, inspired by the design of our specialized algorithm, to obtain an efficient system that can be used as a playground to explore various aspects of attack-defence trees. We compare the two approaches on different benchmarks.

Expressing attack-defence trees in a multi-agent setting allows for studying a new aspect of security scenarios, namely how the number of agents and their task assignment impact the performance, e.g. attack time, of strategies executed by opposing coalitions. Optimal scheduling of agents' actions, a non-trivial problem, is thus vital. We discuss associated caveats and propose an algorithm that synthesises such an assignment, targeting minimal attack time and using the minimal number of agents for a given attack-defence tree. We also investigate an alternative approach for the same problem using Rewriting Logic, starting with a simple and elegant declarative model, whose correctness (in terms of schedule's optimality) is self-evident. We then refine this specification, inspired by the design of our specialised algorithm, to obtain an efficient system that can be used as a playground to explore various aspects of attack-defence trees. We compare the two approaches on different benchmarks.

Expressing attack-defence trees in a multi-agent setting allows for studying a new aspect of security scenarios, namely how the number of agents and their task assignment impact the performance, e.g. attack time, of strategies executed by opposing coalitions. Optimal scheduling of agents' actions, a non-trivial problem, is thus vital. We discuss associated caveats and propose an algorithm that synthesises such an assignment, targeting minimal attack time and using minimal number of agents for a given attack-defence tree.

Summary: The paper is concerned with discrete event‐driven simulation, which is a well‐known technique used for modeling and simulating complex parallel systems. The focus of the paper is on distributed simulation, in which multiple simulated event queues are processed in parallel according to the Time Warp approach. With this approach, parallel simulation based on event queues is allowed to progress in an optimistic way until event correlation errors appear in parallel simulation branches what results in simulation rollbacks. In the absence of synchronization between simulator parallel queues, massive processing rollbacks can strongly slow down simulation. The paper presents a distributed optimistic event‐driven simulation control based on simulator global state monitoring. A systematic control of the simulator global states prevents excessive rollbacks in the Time Warp simulation. Each simulation event queue reports its progress to a global synchronizer which monitors the global simulation state based on virtual timestamps of recently processed events. Based on the global state, the synchronizer checks the simulation progress and sends control signals which asynchronously slow down servicing too advanced queues. The paper describes the principles of the proposed approach and experimental results of its basic program implementation. Comparisons to existing parallel simulation methods are provided.

A new framework for designing evolved program execution control in distributed programs is discussed in the paper. The framework provides an infrastructure for designing distributed program control based on monitoring of global application states. Global control constructs are proposed which logically bind distributed program modules and define the flow of control dependent on the monitoring of global application states. Such control can be organized in programs at the process and thread levels. Special processes and threads called synchronizers collect state information from application modules, construct strongly consistent global states and evaluate control predicates on global states. Based on this evaluation control signals are sent to processes and threads to define inter module flow of control and to influence the internal module behavior. The proposed constructs are incorporated into the framework as a graphical API which is compiled into C/C++ programs with the MPI2, pthreads and Open Mp libraries for communication.