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  1. Apache Arrow
  2. ARROW-6386

[C++][Documentation] Explicit documentation of null slot interpretation

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      To my knowledge, there isn't explicit documentation on how null slots in an array should be interpreted. SQL uses Kleene logic, wherein a null is explicitly an unknown rather than a special value. This yields for example `(null AND false) -> false`, since `(x AND false) -> false` for all possible values of x. This is also the behavior of Gandiva's boolean expressions.

      By contrast the boolean kernels implement something closer to the behavior of NaN: `(null AND false) -> null`. I think this is simply an error in the boolean kernels but in any case I think explicit documentation should be added to prevent future confusion.

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              bkietz Ben Kietzman
              bkietz Ben Kietzman
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