1.
If one argument or fact is ~ another, it is considered in relation to it.
These are relatively small points when ~ her expertise on so many other issues...
PHRASAL VERB: be V-ed P n, also V n P n
2.
To set one person against another means to cause them to become enemies or rivals.
The case has set neighbour against neighbour in the village.
PHRASAL VERB: V n P n