This paper investigates a variation of the reach-avoid game, a multi-agent pursuit and evasion scenario applicable to aerial defense, with faster evaders. Using Deep Reinforcement Learning techniques, the study proposes a different reward function that combines dense (distance-based) and sparse (outcome-based) rewards. Focused on the defender’s perspective in aerial defense, this new reward function resulted in effective learned policies against faster evaders, outperforming traditional differential game and DRL strategies with dense-only rewards. Moreover, the learned policy demonstrated versatility across different instances of the problem, including changes in pursuer speeds and winning radii, illustrating its versatility in unseen situations during training.

Abstract The objective of testing is to determine whether an implementation under test conforms to its specification. In distributed test architectures involving multiple remote testers, this objective can be complicated by the fact that testers may encounter coordination problems relating to controllability (synchronization) and observability during the application of tests. Based on a finite state machine (FSM) specification of the externally observable behaviour of a distributed system and a distinguishing sequence, this paper proposes a method for constructing a checking sequence where there is no potential controllability or observability problems, and where the use of external coordination message exchanges among testers is minimized. The proposed method does not assume a reliable reset feature in the implementations of the given FSM to be tested by the resulting checking sequence.

We introduce a class of networks called Isotach networks designed to reduce the cost of synchronization in parallel computations. Isotach networks maintain an invariant that allows each process to control the logical times at which its messages are received and consequently executed. This control allows processes to pipeline operations without sacrificing sequential consistency and to send isochrons, groups of operations that appear to be received and executed as an indivisible unit. Isochrons allow processes to execute atomic actions without locks. Other uses of Isotach networks include ensuring causal message delivery and consistency among replicated data. Isotach networks are characterized by this invariant, not by their topology. They can be implemented in a wide variety of configurations, including NUMA (nonuniform memory access) multiprocessors. Empirical and analytic studies of Isotach synchronization techniques show that they outperform conventional techniques, in some cases by an order of magnitude or more. Results presented here assume fault-free systems; we are exploring extension to selected failure models.