1. A method of designing a logic circuit for mapping a logical expression, comprising: identifying a first logic group including a first plurality of logic functions and at least one complementary variable shared by the first plurality of logic functions in the logical expression; and mapping the logical expression, including: placing a multiplexer having input terminals, at least one control terminal and an output terminal in the logic circuit; and connecting the input terminals and the at least one control terminal of the multiplexer to input the first plurality of logic functions and the at least one complementary variable so that the first logic group is output from the output terminal of the multiplexer.