Throughout this book, names of variables are referred in italics. The symbol is used to represent ‘the sum of’. For example, the expression can be written as or simply when the range of summation is understood from the context.

In the case of summation involving multiple subscripts, the marginal sums are denoted by placing a dot (.) over that subscript, like,

, ,

When two letters are written side by side such as *ab,* in equations, it generally indicates product of *a* and *b* unless otherwise specified or understood from the context. Multiplication with numerals are indicated by brackets *e.g*., (4)(5) would mean 4 multiplied 5. Division is indicated either by slash (/) or a horizontal mid-line between the numerator and the denominator.

Equations, tables and figures are numbered with reference to the chapter numbers. For instance, Equation (3.1) refers to equation 1 in chapter 3.

Certain additional notations such as those pertaining to factorial notation, combinatorics, matrices and related definitions are furnished in Appendix 7.