: <math>\mathbb{D} = \{(\operatorname{d}a_i), \operatorname{d}a_i\} = \{\mbox{same}, \mbox{different}\} = \{\mbox{stay}, \mbox{change}\} = \{\mbox{stop}, \mbox{step}\}.</math> | : <math>\mathbb{D} = \{(\operatorname{d}a_i), \operatorname{d}a_i\} = \{\mbox{same}, \mbox{different}\} = \{\mbox{stay}, \mbox{change}\} = \{\mbox{stop}, \mbox{step}\}.</math> |