there are 0 cats
in the room. there are 3 cats
in the room. The phrase "there is 1 cat
in the room" is an example of plural's counterpart, singular.
Two halves are better than one, even though two halves is equal to one. While one half is singular, two halves is plural.
And we wouldn't say "two halves are plural".
Yet, two halves are one, is fine.