'''Definition.'''  Let the function <math>\lnot_j : \mathbb{B}^k \to \mathbb{B}</math> be defined for each integer <math>j\!</math> in the interval <math>[1, k]\!</math> by the following equation:  | '''Definition.'''  Let the function <math>\lnot_j : \mathbb{B}^k \to \mathbb{B}</math> be defined for each integer <math>j\!</math> in the interval <math>[1, k]\!</math> by the following equation:  |