You can filter classes by their properties using the checkboxes. An empty checkbox means that classes without that property will be shown. An checked checkbox means that only classes with that property will be shown. A dashed checkbox means that both classes with and without that property will be shown.
For example, checking the "quantum" box will only show classes that are somehow about quantum mechanics. Unchecking the "protocol" box will hide all classes that are, somehow, about prover-verifier interactive protocols.