SVM is originally designed for binary class classification. However,
it can be extended to multi-class problem as applied to RS which is
such a process on most occasions. Usually there are two strategies
to obtain a multi-class pattern recognition system [13]. Several common
multi-class methods for SVM based on these schemes have been
proposed: 1-against-all (1-a-a) [13,17], 1-against-1 (1-a-1) [13], decision
directed acyclic graph (DDAG) SVM [23], and error correcting
output codes (ECOC) [9]. These algorithms can obtain high accuracy;
however, they also result in a time-consuming and tedious parameter
tuning process, even a large unclassifiable region