Artur Czumaj Testing H-freeness in Arbitrary Planar Graphs in Constant Time (Using Random Graph Exploration) Abstract: We consider property testing in general planar graphs, without any bounds for vertex degrees. While testing graph properties in bounded-degree planar graphs is quite well understood, almost nothing is known in the case of general graphs. In this talk, I will prove that the fundamental property of being H-free is constant time testable for every fixed connected subgraph H, in the model when the algorithm can sample random vertices from the input graph and random neighbors of a vertex. Our approach extends to arbitrary minor-free graphs. This is a joint work with Christian Sohler.