Give a regular expression for a certain type of scientific notation for real numbers on which the following rules hold. Let sigma = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "+", "-", e}. a. The number can be preceded by a "+" or "-", sign, or the sign may be absent. b. Numeric values must be of the form cb_1b_2...b_n where b_i is any digit, but c must be nonzero. c. The number may be followed by an exponent field of the form e"+" y_1y_2 or e"-"y_1y_2, where y_1 and y_2 can be any digit in {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}