I am searching for the proper term that describes the following set of criteria:

1) A word starts with "ab" 2) A word starts with "a"


1) The animal is a dog 2) The animal is a canine

As you can see it is not a case of true mutual exclusion because there is only a one-way exclusion. How can this relationship be called?

  • 5
    Actually, there is no exclusion at all. It's rather a matter of inclusiveness. All elements in set 1) are elements in set 2). You could say rule 1) is more specific than rule 2).
    – oerkelens
    Commented Aug 2, 2016 at 15:38

1 Answer 1


From the domain of mathematics, assuming 1) is A and 2) is B:

A is a proper (or strict) subset of B.

or equivalently:

B is a proper superset of A

Alternative terms are inclusion or sometimes containment of A inside B.

As an Euler diagram:

enter image description here



Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.