Frost is the coating or deposit of ice that may form in humid air in cold conditions, usually overnight. In temperate climates it most commonly appears as fragile white crystals or frozen dew drops near the ground, but in cold climates it occurs in a greater variety of forms. ξ1 Frost is composed of delicate branched patterns of ice crystals formed as the result of fractal process development.
The articles in English are the definite article the and the indefinite articles a and an (and sometimes some). Use of the definite article implies that the speaker assumes the listener knows the identity of the noun's referent (because it is obvious, because it is common knowledge, or because it was mentioned in the same sentence or an earlier sentence). Use of an indefinite article implies that the speaker assumes the listener does not have to know the identity of the referent. In some no article is ..
A pinnacle (from Latinpinnaculum, a little feather, pinna, compare panache) is an architectural ornament originally forming the cap or crown of a buttress or small turret, but afterwards used on at the corners of and in many other situations. The pinnacle looks like a small spire. It was mainly used in Gothic architecture.
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.
