Hello –
This statement on "semaphore tower" was incorrect. Errors with basic membership properties create false inferences, such as semaphore tower (Q19850578)subclass of (P279)action (Q4026292). Before using this property, check the item descriptions, and make sure your statement is true in all cases. (In particular, "A" is a subclass of "B" only if all instances of "A" are also instances of "B".) Often, another property can accurately express the relationship you had in mind; in this case, has use (P366) works better. You can search through available properties here. Thanks!