Black Hole Search and Exploration in Unoriented Tori with Synchronous Scattered Finite Automata
نویسندگان
چکیده
We consider the problem of locating a black hole in a synchronous, anonymous, and unoriented torus network using mobile agents. A black hole is a harmful network node that destroys any agent visiting it without leaving any trace. The objective is to locate the black hole using as few agents as possible. We present here an almost optimal deterministic algorithm for synchronous (partially) unoriented tori using five scattered agents with constant memory and three identical tokens. We also study the exploration problem of a safe (i.e., without black holes) unoriented torus. While it has been previously shown that there is no universal algorithm for one agent with constant memory and any constant number of tokens which can explore all cubic planar graphs, we give here the first algorithm which enables a finite automaton with two tokens to explore (without termination detection) any totally unoriented torus and we prove optimality on the number of tokens.
منابع مشابه
Black Hole Search with Finite Automata Scattered in a Synchronous Torus
We consider the problem of locating a black hole in synchronous anonymous networks using finite state agents. A black hole is a harmful node in the network that destroys any agent visiting that node without leaving any trace. The objective is to locate the black hole without destroying too many agents. This is difficult to achieve when the agents are initially scattered in the network and are u...
متن کاملTight bounds for black hole search with scattered agents in synchronous rings
We study the problem of locating a particularly dangerous node, the so-called black hole in a synchronous anonymous ring network with mobile agents. A black hole is a harmful stationary process residing in a node of the network and destroying all mobile agents visiting that node without leaving any trace. Unlike most previous research on the black hole search problem which employed a colocated ...
متن کاملTight Bounds for Scattered Black Hole Search in a Ring
We study the problem of locating a particularly dangerous node, the so-called black hole in a synchronous anonymous ring network with mobile agents. A black hole destroys all mobile agents visiting that node without leaving any trace. Unlike most previous research on the black hole search problem which employed a colocated team of agents, we consider the more challenging scenario when the agent...
متن کاملIdentifying Hostile Nodes in Networks Using Mobile Agents
In distributed mobile computing environments one of the most pressing concerns is security. Two are the most important security threats: a malicious mobile process which can move along the network and a stationary harmful process which resides at a host. One of the most studied models for stationary harmful processes is the black hole which has been introduced by S. Dobrev, P. Flocchini, G. Pre...
متن کاملFault-Tolerant Exploration of an Unknown Dangerous Graph by Scattered Agents
Black hole search (Bhs) is the problem of mapping or exploring a network where there are dangerous sites (black holes) that eliminate any incoming searcher without leaving a discernible trace. Dangerous graph exploration (Dge) extends the Bhs problem to include dangerous links (black links). In the literature, both problems have only been studied under the assumption that no faults occur in the...
متن کامل