[Om3] trouble with container markup example

[Paul Libbrecht]

Le 11-févr.-09 à 23:53, Professor James Davenport a écrit :
>> You are absolutely right Robert,
>> and I fear that both OpenMath and MathML content are having
>> subset_suchthat (the set of things inside a reference set such that
>> some condition holds) but miss
>>   set_of_expressions_such_that
> The reason fro this, as I recall, is to avoid Russell's paradox.

But you do not hit the Russel's paradox since the
   set_of_expressions_such_that( x, domain, f )
   = map(f,suchthat(x,domain))

The issue is having to use map, I think where one wishes to speak of  
the set of function-results and not speak about applying f to the set.

Map sounds like it should be called range to me... but that is  
superficial.

paul

>> To serve the purpose below ( {[0,x] | x in R} )
> Surely this is map(lambda x.interval(0,x),R).
>> and many others where basically one constructs a set by applying
>> functions to a few other sets. I think { [x,y] | x in R and y in R }
>> is even more difficult.
> Non-trivial, but basically because cartesian product don't have
> deconstructors.
> map(lambda z,interval(z.first,z.second),cartesian_product(R,R))
> is basicaly what is wanted.
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