• Catt
    link
    fedilink
    arrow-up
    12
    ·
    edit-2
    4 days ago

    Nope, the text is correct.

    not (x or y) <=> (not x) and (not y)
    not (x and y) <=> (not x) or (not y)
    

    Edit: The parenthesis on the right side if the equivalence are only there to make it easier to read. Without those, the expression would be the same in this case