How to check for geometrical isomerism in cyclic compounds?
I hope the statutes of limitation haven't run out. Structure 1 is a (Z)-alkene. Using Cahn-Ingold-Prelog (CIP) protocol, the rings are deconstructed as shown in diagram 2. The larger red arrow marks the higher priority carbon (C,C,C). The smaller red arrow points to the lower priority[carbon (C,H,H). For the blue arrows, sulfur takes priority over carbon. [Addendum: Strictly speaking, the two blue arrows should point to the methylene groups next to the blue sp2 carbon such that C(S,H,H) > C(C,H,H).] The two larger arrows establish a (Z)-configuration. See: What are the CIP rules for cyclic substituents?