Tanis said:
Catholics are Christians.
/=/ means 'not'.
So, by your very post you were saying either 'Christians aren't Catholics' or 'Catholics aren't Christians'.
≠ doesnt mean "not". It means "not
equal". In this case thats important, because for something to be equal they need to be identical, not just one being a subset of the other.
"Catholic ≠ Christian" is correct. For Catholic to
equal Christian would require that
all Christians be Catholics, and conversely saying "Catholic ≠ Christian" only means "not
all Christians are Catholic".
Monster_user said:
Which is correct?
Consider that 5 is the number, and that 1 is considered to be a part of 5 (1,1,1,1,1) or (1,4).
Thats a strange way of phrasing it, but if we accept your phrasing I would go with option 3 - a different symbol. Namely, I would say "1 ∈ 5", where ∈ means "an element of the set", since youve kind of phrased the question so that 5 is a set of smaller numbers.