Optional levels in the domain model

[agazzarini]

The RRE domain/data model provides a hierarchy with several levels (corpus, topic, query group, query and metrics).

Although this could be helpful when you need to model a rich domain, sometimes that results in a lot of redundancy (e.g. query groups and queries have the same cardinality).

It would be great if the ratings file would allow to exclude one or more levels, with the edge case where we have only queries.

[agazzarini]

topics and query_groups are now optional in the RRE domain model. That allows a high level of flexibility when defining the ratings set. Specifically (wiki will be updated asap) the domain model supports one of the following:

• n topics -> n query groups -> n variant queries (i.e. logical variants of the same query)
• n query groups -> n variant queries
• n variant queries

In case one level is missing, RRE will create a unnamed node. So for example, if topics are missing, all defined query groups will belong to an "Unnamed" topic; if query groups are missing queries will belong to an "Unnamed" query group which in turn will belong to an "Unnamed" topic.

In this way the domain model is always consistent, and a report could easily hide those "Unnamed" layers

[agazzarini]