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.
A subgroup is a subset of group elements of a group that satisfies the four group requirements. It must therefore contain the identity element. is a subgroup of  is written , or sometimes (e.g., Scott 1987, p. 16). The order of any subgroup of a group of order must be a divisor of . A subgroup of a group that does not include the entire group itself is known as a proper subgroup, denoted or .