In mathematical language, you are expecting a symmetric difference, but 
what people in the math dept I learned in usually mean by set difference 
is what Squeak seems to be doing. Wikipedia seems to agree [1].


[1] http://en.wikipedia.org/wiki/Complement_%28set_theory%29


Daniel


cdrick wrote:

>
>
> 2007/12/12, cdrick <cdrick65 at gmail.com <mailto:cdrick65 at gmail.com>>:
>
>     just playing around:
>
>     (#(1 2 3) asSet) difference:  (#(1 2 3 4 5) asSet)                
>     a Set()
>
>
> to be more complete:
>
> #(1 2 9) asSet difference: #(1 3) asSet                 a Set(2 9)
> #(1 2 3 9) asSet difference:  #(1 2 3 4 5) asSet     a Set(9)
>
> is it the right definition of set differece ? 
> aren't we expecting   union minus intersection ?
>
>
> ------------------------------------------------------------------------
>
>
>