• Ep1cFac3pa1m@lemmy.world
    21·
    11 months ago

    If Nazi, then fascist = true

    Fascist, if and only Nazi = not true

    If car, then vehicle = true

    Vehicle if and only if car = not true

    • Lafari@lemmy.worldOP
      2·
      11 months ago

      If car, then vehicle = true

      Car if and only if vehicle = true.

      Is this correct?

      Therefore “If A then B” = “A if and only if B” (or “If B then A” = “B if and only if A”)?

      • zenharbinger@lemmy.world
        6·
        11 months ago

        B can still be true when a is false. iff means that b can only be true when a is true.

        Also, the equivalent statement is.

        vehicle if and only if car.

        not

        car only if vehicle

        since a truck is a vehicle, the statement is false.

        Somewhat wrong above:

        A B a iff b

        T T T

        T F F

        F T F

        F F T

        look online for truth tables.

      • Ep1cFac3pa1m@lemmy.world
        3·
        11 months ago

        You’d have to firm up your definition of car and vehicle before you could decide that one. Does a hot wheels car count as a car? Does a vehicle have to be large enough to move people or freight?