Page 190 - Introduction to Statistical Pattern Recognition
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172                        Introduction to Statistical Pattern Recognition






























                      complicated to be practical.  Therefore, we  will limit our discussion to convex
                      regions here.
                           The probability of  error for each class,  E;,  can be  expressed in  terms of
                      the (L - 1)-dimensional distribution function as

                                                  >
                                  E;  = 1 - Pr(h;,(X) 0,. . .,hiL(X) > OIX E  0;)
                                    = I - [- . .[-p (h; 1,  . . . ,h;L I 0;)dh; . . . dh,   (4.156)
                                            .
                                                                   I
                                                [hii(X) is excluded] .
                      The total error is

                                                     L
                                                 E = ZP;E; .                     (4.157)
                                                     i=l
                           Knowing the structure of piecewise linear classifiers, our problem is how
                      to design the  V’s  and  YO’S for a given set of  L  distributions.  Because of  the
                      complexity  involved,  solutions  for  this  problem  are  not  as  clear-cut  as  in  a
                      linear classifier.
                           Three approaches are mentioned briefly:
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