Q: Relational override on 'objects'? I have a signature
sig Test {
    a: Int,
    b: Int,
    c: Int
}

If I have two instances (atoms?) of this ( x,y:Test )
can I define a relation between these where only some parameters has changed without having to list all the other parameters as equal?
I want to avoid having to list all unchanged fields
as this can be error-prone assuming I have many fields.
Currently I am using x.(a+b+c) = y.(a+next[b]+c) but would like to use something like x = y ++ (b->next[y.b])

A: from what I understand about Alloy I think the answer is No: you cannot talk about all relations where some atom is involved in without explicitly naming these relations. But some experts may correct me if I'm wrong.
