Don't Be Afraid to Die: Black Hole Search in Dynamic Graphs with Fewer Agents

Abstract

We consider a team of synchronous mobile agents operating in a port-labeled network. There is one node in the network, called a black hole, that permanently destroys any agent that visits the node. The team of agents must safely locate the black hole, i.e., at least one agent must survive, terminate its algorithm at a node adjacent to the black hole, and output the port number that leads to the black hole from its current position. In the setting where the network is a 1-bounded 1-interval connected dynamic graph, Kaur et al. (SSS 2025) showed that a team consisting of $2\delta_{BH}+17$ agents is sufficient to solve the task from a scattered configuration, where $\delta_{BH}$ denotes the degree of the black hole node. We show that $2\delta_{BH}+3$ agents are sufficient, nearly matching the $2\delta_{BH}+1$ lower bound provided in Kaur et al. (ICDCN 2025).