The chapter presents an approach to agent indirect interaction in smart space based on the publication/subscription mechanism. It is proposed to describe every agent with an ontology and support the ontology matching between ontologies of different agents in smart space to enrich the semantic interoperability between them. When the agents reach the semantic interoperability, they are aimed to create a coalition to perform a task. The task is described by ontology and the agents determine what they can propose to implement it. Group of agents that can perform the task together is called coalition. The considered case study describes the mobile robot interaction for the case of joint obstacle overcoming by the 6WD robot with lifting chassis, quadrocopter that scans an obstacle, and knowledge base service that contains algorithms for obstacle overcoming.