Autosymmetry [1] is useful in minimizing certain Boolean functions. Autosymmetry is detected using closed functions. Here we show that singular GF (2) matrices can be used for the same purpose, and that this approach also permits the use of the universal symmetry detector [2] to detect autosymmetric functions. Autosymmetric functions can generally be implemented more efficiently than ordinary Boolean functions, so detection of autosymmetry is useful in the efficient implementation of Boolean logic.