In this letter, we report on the fabrication and characterization of ambipolar silicon-nanowire (SiNW) field-effect transistors (FETs) with a double-independent-gate (DIG) structure for polarity control. Several structures are fabricated, showing the effectiveness of local back gate to enable switchable ambipolar functionality. Moreover, and, nand, nor, xor, and xnor binary logic functions can be obtained with a single gate, depending on the encoding values used for the input signals. Repeatable behaviors of DIG SiNW FETs are considered as enablers for ambipolar-controlled logic, with all the benefits related to the maturity of the silicon technology.