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oscarlevin / discrete-book

An open textbook for Discrete Mathematics, as taught at the University of Northern Colorado
http://discrete.openmathbooks.org/dmoi3.html
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Confusing language about inclusive “or”? #114

Open lbeaufort opened 3 years ago

lbeaufort commented 3 years ago

Hi there! I’m really enjoying your online textbook, thank you for making it free online and providing helpful exercises and examples!

I came across the language:

Note that for us, or is the inclusive or (and not the sometimes used exclusive or) meaning that P ∨ Q and P ∨ Q is in fact true when both P and Q are true.

Source: http://discrete.openmathbooks.org/dmoi3/sec_intro-statements.html#wKm

This language was a bit confusing to me, as I’m re-learning discrete math after 15 years. It might be less confusing to say:

Note that for us, or is the inclusive or (and not the sometimes used exclusive or) meaning that P ∨ Q and P ∨ Q is true ~in fact~ when both P and Q are true and when either P or Q is true.

If you agree, I’d be happy to put in a pull request. Thanks again!

davidfarmer commented 3 years ago

I think it is more clear to say it in the other order:

P ∨ Q is in fact true when P is true, or when Q is true,
or when both are true.

Maybe it would be good to go on to talk about what exclusive or means (and give a symbol to it), and then start a new paragraph with the discussion of "and"?

On Sun, 6 Dec 2020, Laura Beaufort wrote:

Hi there! I’m really enjoying your online textbook, thank you for making it free online and providing helpful exercises and examples!

I came across the language

  Note that for us, or is the inclusive or (and not the sometimes used exclusive or)
  meaning that P ∨ Q and P ∨ Q is in fact true when both
  P and Q are true.

Source: http://discrete.openmathbooks.org/dmoi3/sec_intro-statements.html#wKm

This language was a bit confusing to me, as I’m re-learning discrete math after 15 years. It might be less confusing to say:

  Note that for us, or is the inclusive or (and not the sometimes used exclusive or)
  meaning that P ∨ Q and P ∨ Q is true in fact when both
  P and Q are true and when either P or Q is true.

If you agree, I’d be happy to put in a pull request. Thanks again!

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oscarlevin commented 3 years ago

Good idea @davidfarmer , and thanks @lbeaufort for the suggestion. I'll clean this paragraph up as I work on the new edition.