Given a proposition co that has the positive polarity, namely co+ , its negation := has the negative polarity; we represent this as 1)01() = -, or Using this notation, we can state the principle of double negation: Given a proposition with the negative polarity (p-, its negation //) := ---,co has the positive polarity, namely 0+.
this principle of double negation implies that and co have the same polarity, and so do and the polarity "flip-flops" depending on whether the number of negations is even or odd.