synonym reference edges with type = pub

[dosumis]

Large numbers of synonym edge links to pubs are ending up typ=def.

This is happening because annotation axiom addition uses the simple wrapper = merge. This overwrites 'typ={some synonym type}' with typ='def' every time a definition is processed after a synonym.

Potential solution:

• typ --> list to which items are appended. So an edge can be both syn and def. Note def values are handled separately on node.

[dosumis]

CC @Robbie1977

[dosumis]

From discussion with Robbie:

1. Multiple types on edges isn't safe. What if the same paper has different types of synonym?
2. Proposed solution (from discussion with Robbie): Use bespoke edge types - exact_synonym_reference, definition_reference etc. Where one pub has more than one synonym of a particular type these can just be listed under value.