Then for any subset A of U, the complement of A (symbolized by A′ or U − A) is defined as the set of all elements in the universe U that are not in A. For example, if the universe consists of the 26 letters of the alphabet, the complement of the set of vowels is the set of consonants.
For any subset, we denote (2.2).
Indeed, for any subset with (3.11).
For any subset, we use to denote the Lebesgue measure of.
Finally, we can easily extend this argument for any subset of links l i (G).
Clearly, and for any subset of furthermore, if is finite, then.
For any subset of, the upper inverse and the lower inverse are defined by and, respectively.
For any subset U⊆V, let q(U) be the number of connected components in G(U).
For any subset G of X, we denote by intG its interior and (overline{G}) its closure, respectively.
Given a set system, for any subset of the points, let denote the projection of onto, that is, the set.
For any subset K of N of cardinality (kleq n) we define an ((n-k -simplex (Delta^{[K]}) as follows.
