Add chain rules for mappings

[cthoyt]

Mapping Chains

Transitivity of equivalence

• A skos:exactMatch B and B skos:exactMatch C implies A skos:exactMatch C

Inversion

• A skos:exactMatch B implies B skos:exactMatch A
• A skos:broadMatch B implies B skos:narrowMatch A
• A skos:narrowMatch B implies B skos:BroadMatch A

Broad

• A skos:exactMatch B and B skos:broadMatch C implies A skos:broadMatch C
• A skos:broadMatch B and B skos:exactMatch C implies A skos:broadMatch C

Narrower

• A skos:exactMatch B and B skos:narrowMatch C implies A skos:narrowMatch C
• A skos:narrowMatch B and B skos:exactMatch C imples A skos:narrowMatch C

Nothing

-` skos:broadMatch skos:narrowMatch -> no

TODO

• add more chains for related, like owl:equivalentTo? Or is it good enough to say these are the same as skos:exactMatch

@matentzn feel free to edit the issue in place for adding more