The compound is named as bicyclo[x.y.z]alkane. Total carbons = 8 (octane). The bridgehead carbons are the two carbons where the rings join. The numbers x, y, z represent the number of carbons on the three paths between the bridgeheads, in descending order. Here, the paths have 4, 2, and 0 carbons. So, it is Bicyclo[4.2.0]octane.