A question about the definition of 'set'

[murshid]

A set is defined as: "A set is a finite or infinite collection of objects in which order has no significance, and multiplicity is generally also ignored (unlike a list or multiset)." (link)

 

This is my question: can it be a collection of real objects or does it have to be a collection of abstract or conceptual objects only?

[ajb]

As it is mathematics, the domain is really abstract. However, it is often the case that abstract ideas can be applied to nature and real world situations.

 

If I have a collection of fruit, lets say an orange, an apple and a banana, then I can describe this real world situation with a set, say [math]F = \{ O, A, B \}[/math] (with obvious notation). But this set is an abstract construction and the fruit physical objects.