Full Idea
The argument from P to A is 'relevantly' valid if and only if, for every situation in which each premise in P is true, so is A.
Gist of Idea
It's 'relevantly' valid if all those situations make it true
Source
JC Beall / G Restall (Logical Pluralism [2006], 5.2)
Book Reference
Beall,J/Restall,G: 'Logical Pluralism' [OUP 2006], p.53
A Reaction
I like the idea that proper inference should have an element of relevance to it. A falsehood may allow all sorts of things, without actually implying them. 'Situations' sound promising here.