?-Paired dominating graphs of lollipop, umbrella and coconut graphs

A paired dominating set of a graph G is a dominating set whose induced subgraph has a perfect matching. The paired domination number 7pr(G) of G is the minimum cardinality of a paired dom-inating set. A paired dominating set D is a 7pr(G)-set if D = 7pr(G). The 7-paired dominating graph PD,y(G) of G is the graph whose vertex set is the set of all 7pr(G)-sets, and two 7pr(G)-sets D1 and D2 are adjacent in PD,y(G) if D2 = (D1 \ {u}) U {v} for some u E D1 and v E/ D1. This paper determines the paired domination numbers of lollipop graphs, umbrella graphs, and coconut graphs. We also consider the 7-paired dominating graphs of those three graphs.