Daniel Lewis <elderdanlewis <at> gmail.com> writes:

> 
>       Let me see if I understand what you want to do.  You are use to 
> writing  xRy to mean that the ordered pair (x,y) is a member of the 
> relation R. For example, let the relationship R be the square function: 
> y=x². Then (2,4), (3,9), and (4,16) are all members of this relation. In 
> OOo's Math this would be written as (2,4) in R,  (3,9) in R, and (4,16) 
> in R. Math replaces the "in" with an epsilon.  Similarly, (5,21) notin R 
> states that the ordered pair (5,21) is not in the relationship defined. 
> Math replaces the "notin" with an epsilon having a forward slash through it.
>       If I understand the use of xRy in MS Word, it refers only to 
> relations that are binary. Math on the other hand allows for relations 
> which includes three or more variables as in (x,y,z) in R, (w,x,y,z) in 
> R, etc.
>       Perhaps this will help. Otherwise, you need to be very specific as 
> to what xRy means in MS Word.
> 
> Dan
> 
(...)

Hi Daniel. Thanks for the reply.

You're right xRy means (x,y) in R. But compare the verbosity. xRy is not an MS
Word notation. It is a mathematical, well established one (see
https://secure.wikimedia.org/wikipedia/en/wiki/
Relation_%28mathematics%29#Formal_definition).
x("slashed" R)y means (x,y) notin R, and is well established too. Of course,
this notation is limited to binary relations. But I work with them most of time.
With MS Word, I can write (x,y,b,...) in R whenever I need. There is no such
limitation. What seems to be a limitation here is that OO Math doesn't let me do
a thing like

x "slash" Ry

though I can do

x bar Ry

or

x overstrike {R}y

This "slash" feature allow to graphically "negate" any symbol (whatever it
means). For example,

P equiv Q

might be negated (and *may* in MS Word) writing

P "slash" equiv Q

even if there is no predefined symbol do negate the equivalence.

Have I been clear?

Is there a "hidden" way of doing that in OO Math?

Thanks again.


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