2. The system according to claim 1, in which said if-part membership values producing means comprises: first subtracting means for calculating .vertline.xo-xi.vertline. from the point of change xo and the binary data xi; multiplying means for calculating k.multidot..vertline.xo-xi.vertline. from the output of said first subtracting means and the tangent k; and second subtracting means for calculating c-k.multidot..vertline.xo-xi.vertline. from the output of said multiplying means and a predetermined value C, the output of said second subtracting means serving as the if-part membership value.
2. The system according to claim 1, in which said if-part membership values producing means comprises: first subtracting means for calculating .vertline.xo-xi.vertline. from the point of change xo and the binary data xi; multiplying means for calculating k.multidot..vertline.xo-xi.vertline. from the output of said first subtracting means and the tangent k; and second subtracting means for calculating c-k.multidot..vertline.xo-xi.vertline. from the output of said multiplying means and a predetermined value C, the output of said second subtracting means serving as the if-part membership value. 4. A system according to claim 2, in which said if-part membership values producing means further comprises logic gate means which receives the output k.multidot..vertline.xi-xi.vertline. of the multiplying means and an overflow output of the multiplying means, the output of said logic gate means being supplied to said second subtracting means as the output of said multiplying means.