I was wondering if anyone could help me out here. Always had trouble understanding this concept.

1. Say I am negating [A and B]. I know this turns to [/A or /B]. Does this or mean that BOTH A and B are out? I know it means either A is out, or B is out but can both possibly be out?

2. Conversely, if I was negating [/A and /B], I know this becomes A or B. Does this or mean that BOTH A and B could possibly be in? I know it means either A is in, or B is in, but can both possibly be in?

Not entirely sure when the "inclusive" or applies or not. Thanks a lot guys!

3

9 comments

  • Sunday, Apr 24 2016

    @quinnxzhang542 Great explanation.

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  • Sunday, Apr 24 2016

    @7rbg180885 @quinnxzhang542 Thanks for the help, guys! Really grateful how awesome this community is.

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  • Sunday, Apr 24 2016

    @7rbg180885 Also, I'm assuming that the only time that "or" is not inclusive is when they specifically say "not both"?

    This might be obvious, but the other instance where "or" is not inclusive is when either laws of nature or other rules/games setup preclude "both" from happening.

    A is in Paris or London (definitely not both)

    Game setup: There are no ties. A or B is third -->not both, because there are no ties.

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  • Sunday, Apr 24 2016

    To modify the answer you were given, sometimes the "or" is a de facto exclusive-or. For example, if a rule tells you that Molly finished first or fifth, you can interpret that to be an exclusive-or. This is because you know that Molly couldn't have finished both first and fifth.

    However, when it's possible for both disjuncts to be true, you should interpret the "or" as an inclusive-or unless otherwise stated.

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  • Saturday, Apr 23 2016

    @ioana200 Got it. Thanks again!

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  • Saturday, Apr 23 2016

    Yes. Assume that "or" is inclusive unless explicitly stated otherwise (i.e. "not both").

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  • Saturday, Apr 23 2016

    @ioana200 Also, I'm assuming that the only time that "or" is not inclusive is when they specifically say "not both"? Is that a correct assumption? Or are there instances where they may not specify but the "or" is exclusive?

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  • Saturday, Apr 23 2016

    @ioana200 Thank you so much for the help!

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  • Saturday, Apr 23 2016

    "Or" in both cases is inclusive, so yes to both questions.

    1.) Both could be out

    2.) Both could be in

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