WebMath: Re: notations for minus

[Allan Hayes]

It seems that three uses for - have been raised,  illustrated by
        the negative number  -7
        the unary function    -(7)
        the binary subtraction function in infix notation    8 - 7
We have
        -(7) = -7  and -(-7) = 7
and the reduction
        8 - 7 = 8+(-(7)) = 8+ (-7) = 1.

With multiplicaton we have, using ^ to denote superscript,
        2^-1
        (2)^-1
        3/2  = 3 * ((2)^-1) = 3* (2^-1)

But do we interpret  1/2 as (2)^-1 or as 2^-1.

It seems that where necessary parentheses are enough to distinguish them

Allan

---------------------
Allan Hayes
Leicester UK
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565


----- Original Message -----
From: "Stan Devitt" <jsdevitt at stratumtek.com>
To: <webmath at camel.math.ca>
Sent: 22 July 2002 21:12
Subject: Re: notations for minus (was WebMath: Fwd: BOUNCE webmath at west.camel.math.ca:)


> And for the record,  the distinction between negative and minus
> in content mathml is that one is a unary application of <minus/>
> and the other is a binary application.
>
> This begs the question of  searching for a standard way
> of displaying the distinction,  but given that there may be more
> than one stylistic convention, it does illustrate
> how one can separate the two issues
> without losing track of the mathematical distinction
> and without risking a mis-interpretation of any
> given style.
>
> Stan Devitt
>
>
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