[Om] Tuple and list : any distinction?

Joe Collins joseph.collins at nrl.navy.mil
Thu Feb 18 19:28:48 CET 2010

Dear James,

The list constructor "suchthat"
takes a set as input and a boolean indicator function over the set.

There is no defined order so the result cannot be well defined if order is an 
essential property of lists.

This is probably OK if one doesn't care about the order of the result in this case.

Presumably, if one wants to be more formal, an order relation is also a required 
argument. To truly nitpick, the number of equivalence classes of the order 
relation over the set must be the same as the cardinality of the set, i.e., no 
two items in the set are "equal" under the order relation.


Professor James Davenport wrote:
> On Wed, February 17, 2010 1:51 pm, Joe Collins wrote:
>> The OpenMath ecc CD defines Tuple and the list1 CD defines list.
>> Is there any essential distinction between Tuple and list?
>> If so, what?
> Michael's given the 'philosophical' answer better than I could.
>> Some of the definitions in list1, list2 suggest (to me) that the order of
>> the list elements are arbitrary. Is this actually the case?
> That's NOT meant to be the case - can you point me at the problems?
> James Davenport
> Recently: Visiting Full Professor, University of Waterloo
> Now back as:
> Lecturer on XX10190, CM30070, CM30078/50123, CM50209
> Hebron & Medlock Professor of Information Technology, University of Bath
> OpenMath Content Dictionary Editor and Programme Chair, OpenMath 2009
> IMU Committee on Electronic Information and Communication

Joseph B. Collins, Ph.D.
Code 5583, Adv. Info. Tech.
Naval Research Laboratory
Washington, DC 20375
(202) 404-7041
(202) 767-1122 (fax)
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