quemb.shared.typing.OriginIdx

quemb.shared.typing.OriginIdx = quemb.shared.typing.OriginIdx

In a given BE fragment, this is the origin of the remaining fragment after subsets have been removed. Since a fragment can swallow other smaller fragments, there is only one origin per fragment but multiple centers, which are the origins of the swallowed fragments.

In the following example, we have drawn two fragments, one around atom A and one around atom B. The fragment around atom A is completely contained in the fragment around B, hence we remove it. The remaining fragment around B has the origin B, and swallowed the fragment around A. Hence its centers are A and B. The set of edges is the complement of the set of centers, hence in this case for the fragment around B the set of edges is the one-element set {C}.

__________
|        |  BE2 fragment around A
|        |
___________________
|        |        |   BE2 fragment around B
|        |        |
A ------ B ------ C ------ D
|        |        |        |