We consider the task of testing whether a Boolean function $f:\{0,1\}^\ell\to\{0,1\}$
is the indicator function of an $(\ell-k)$-dimensional affine space.
An optimal tester for this property was presented by Parnas, Ron, and Samorodnitsky ({\em SIDMA}, 2002), by mimicking the celebrated linearity tester (of Blum, Luby and Rubinfeld, {\em JCSS}, 1993) ... more >>>