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Re: [mathonweb] reminder: meetings this week

From: Volker Sorge <volker.sorge@gmail.com>
Date: Mon, 10 Sep 2018 21:33:20 +0100
Message-ID: <CAE5-06QxpLtaBaaGcF+b-u5LJya8TvZy8xKNVRaRdUJg9DVRBA@mail.gmail.com>
To: "Pedersen, John - Hoboken" <jpederse@wiley.com>
Cc: Neil Soiffer <soiffer@alum.mit.edu>, Peter Krautzberger <peter@krautzource.com>, mathonweb <public-mathonwebpages@w3.org>
I might be wrong then. All I can find quickly is Geoff Sutcliffe's page
(some way down):
http://www.cs.miami.edu/home/geoff/Courses/COMP6210-10M/Content/Propositional.shtml
I also seem to recall from reading Frege that he does not define an order.
But it's been a while since I've read Begriffsschrift.
Anyway, I generally teach my students to better check the definitions
before assuming an order on those two connectives with any author. (And I
require them to use parentheses.)

Best,
Volker

On Mon, 10 Sep 2018 at 21:20, Pedersen, John <jpederse@wiley.com> wrote:

> Although it’s been a while, I did teach undergraduate and graduate-level
> logic and algebra for a number of years and I have the same understanding
> as Neil that in propositional, first, and higher-level logics, conjunction
> has priority over disjunction. There are numerous classic texts where this
> is given as the rule. Can you point to any text or other source where the
> order is stated to be different?
>
>
>
> *From:* Volker Sorge <volker.sorge@gmail.com>
> *Sent:* Monday, September 10, 2018 3:51 PM
> *To:* Neil Soiffer <soiffer@alum.mit.edu>
> *Cc:* Peter Krautzberger <peter@krautzource.com>; mathonweb <
> public-mathonwebpages@w3.org>
> *Subject:* Re: [mathonweb] reminder: meetings this week
>
>
>
> I am confused; I don't understand your point. I was explicitly referring
> to classical logic.
>
> Of course you can define a precedence order. Programming languages often
> do following Boolean algebra habits, so do often authors of logic text
> books. But even then the order between and/or can depend on the author.
>
>
>
>
>
>
>
> On Mon, 10 Sep 2018 at 19:10, Neil Soiffer <soiffer@alum.mit.edu> wrote:
>
> I disagree about there not being an accepted precedence for * and* vs *or*.
> The precedence in programming languages that I know all have *and *with a
> higher precedence than *or*. In MathML, the default operator table does
> so also. The other notation used for logical and/or is  ·/+ (as in a ·b + c
> or ab+c) and these again use the convention that the "times" operator has a
> higher precedence than "plus" for and/or.
>
>
>
> It may be that some books/articles do it the other way around, but I'd
> like to see some examples proving me wrong. Or if they are considered equal
> precedence, again, I'd like to see some examples where this is true (as
> opposed to just using parens to make it clearer).
>
>
>
>     Neil
>
>
>
>
>
> On Mon, Sep 10, 2018 at 10:55 AM, Volker Sorge <volker.sorge@gmail.com>
> wrote:
>
> There is no precedence order for logical and/or ∧/∨.
>
> Precedence in classical logic is: negation over conjunction/disjunction
> over (material) implication over equivalence.
>
> You always need to disambiguate order of and/or.
>
> Volker
>
>
>
> On Mon, 10 Sep 2018 at 18:33, Neil Soiffer <soiffer@alum.mit.edu> wrote:
>
> Apologies for missing the meeting today -- I don't seem to have the
> meetings properly entered into my calendar and due to the time difference,
> I don't see Peter's reminders until after I start work.
>
>
>
> I have a question about what someone wrote on the Wiki:
>
>      a∧b∨c it is not clear the order precedence. Usually ∧ has precedence
> over ∨, but not always.
>
>
>
> Can someone clarify (on the wiki) *when* it the normal precedence doesn't
> hold. What surprised me when I first looked into notations and precedence
> (20 years ago -- yikes!) was that although a symbols might have many
> different meanings, the precedence relationships it has didn't seem to
> change. I attributed that to people trying to avoid confusion when using
> familiar notation for new functionality. Having '∨' have a different
> precedence relative to '∧' in some cases seems very strange to me. But
> mathematicians do strange things at times (especially logicians ;-).
>
>
>
>     Neil
>
>
>
>
>
>
> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
>
> Virus-free. www.avg.com
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>
>
>
> On Mon, Sep 10, 2018 at 12:36 AM, Peter Krautzberger <
> peter@krautzource.com> wrote:
>
> Hi everyone,
>
>
>
> Just a quick reminder for the CG meetings this week.
>
>
>
> - a11y TF, Monday, Sept 10, 11am Eastern
>
> - css TF, Monday, Sept 10, 12pm Eastern
>
> - no CG meeting this week
>
>
>
> Best,
>
> Peter.
>
>
>
>
>
>
Received on Monday, 10 September 2018 20:33:55 UTC

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