The first order differential extension of <math>\mathcal{X}</math> is <math>\operatorname{E}\mathcal{X} = \{ x_1, \operatorname{d}x_1 \} = \{ A, \operatorname{d}A \}.</math> If the feature <math>A\!</math> is understood as applying to some object or state, then the feature <math>\operatorname{d}A</math> may be interpreted as an attribute of the same object or state that says that it is changing ''significantly'' with respect to the property <math>A,\!</math> or that it has an ''escape velocity'' with respect to the state <math>A.\!</math>. In practice, differential features acquire their logical meaning through a class of ''temporal inference rules''. | The first order differential extension of <math>\mathcal{X}</math> is <math>\operatorname{E}\mathcal{X} = \{ x_1, \operatorname{d}x_1 \} = \{ A, \operatorname{d}A \}.</math> If the feature <math>A\!</math> is understood as applying to some object or state, then the feature <math>\operatorname{d}A</math> may be interpreted as an attribute of the same object or state that says that it is changing ''significantly'' with respect to the property <math>A,\!</math> or that it has an ''escape velocity'' with respect to the state <math>A.\!</math>. In practice, differential features acquire their logical meaning through a class of ''temporal inference rules''. |