Multiplicative Complexity of Vector Valued Boolean Functions
Joan Boyar, Magnus Gausdal Find
Theoretical Computer Science.

We consider the multiplicative complexity of Boolean functions with multiple bits of output, studying how large a multiplicative complexity is necessary and sufficient to provide a desired nonlinearity. For so-called ΣΠΣ circuits, we show that there is a tight connection between error correcting codes and circuits computing functions with high nonlinearity. Combining this with known coding theory results, we show that functions with n inputs and n outputs with the highest possible nonlinearity must have at least 2.32n AND gates. We further show that one cannot prove stronger lower bounds by only appealing to the nonlinearity of a function; we show a bilinear circuit computing a function with almost optimal nonlinearity with the number of AND gates being exactly the length of such a shortest code. Additionally we provide a function which, for general circuits, has multiplicative complexity at least 2n-3. Finally we study the multiplicative complexity of ``almost all'' functions. We show that every function with n bits of input and m bits of output can be computed using at most 2.5(1+o(1))sqrt(m 2n) AND gates.

Last modified: Tue Jun 3 16:48:05 CEST 2014