Some road type classifications are influenced by city size, traffic density, and regional conventions. For example, in a very large city a primary street may have three or more lanes in each direction on a divided road. While in a town of dirt roads, the only paved single lane street could be a primary street.
subset - a set whose members are members of another set; a set contained within another set. set - (mathematics) an abstract collection of numbers or symbols; the set of prime numbers is infinite. Translations. podmnoÅ¾ina.
1 Any set is a subset of itself, but not a proper subset. (X â X is true, and X â X is false for any set X.)  The empty set { }, denoted by â, is also a subset of any given set X. It is also always a proper subset of any set except itself.