Rodents are of the orderRodentia, characterised by a single pair of continuously growing incisors in each of the upper and lower jaws that must be kept short by gnawing.
In mathematics, especially in set theory, a setA is a subset of a set B, or equivalently B is a superset of A, if A is "contained" inside B, that is, all elements of A are also elements of B. A and B may coincide. The relationship of one set being a subset of another is called inclusion or sometimes containment.
