Re: relations aren't types?

"Bob Badour" <bbadour_at_golden.net> wrote in message news:<U5-dnfKDdMPabWuiRVn-tw_at_golden.net>...

> > No, the contrary. I mean they have visible "structure", but not
> > possible representations.
> >
> > What are the possible representations of a relation value?
>
> One possible representation has a header and a body where THE_header is a
> set of attribute name/data type pairs and where THE_body is a set of sets of
> attribute name/data type/value triplets.

No, it is not a possible representation of a relation, it is a description of the structure of a relation.

Lets try again:

scalar

A quantity, such as mass, length, or speed, that is completely specified by its magnitude and has no direction. Mathematics. A number, numerical quantity, or element in a field.

Source: The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2000 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

scalar

adj : of or relating to a directionless magnitude; "scalar implicatures" n : a variable quantity that cannot be resolved into components

Source: WordNet ® 1.6, © 1997 Princeton University

scalar

1. <mathematics> A single number, as opposed to a vector or matrix of numbers. Thus, for example, "scalar multiplication" refers to the operation of multiplying one number (one scalar) by another and is used to contrast this with "matrix multiplication" etc.
2. <programming> Any data type that stores a single value (e.g. a number or Boolean), as opposed to an aggregate data type that has many elements. A string is regarded as a scalar in some languages (e.g. Perl) and a vector of characters in others (e.g. {C}).

www.dictionary.com

scalar

1. In mathematics, scalar (noun) and scalar (adjective) refer to a quantity consisting of a single real number used to measured magnitude (size). Voltage, mass, and temperature measurements can be described as scalar quantities.

http://whatis.techtarget.com/definition/0,,sid9_gci330659,00.html

It seems clear that scalar is a math term which means a single quantity without structure or components.

In programming terminology the concept was generalized to any value that cannot be resolved into components.

So it is evident that integer, rational, quaternion, temperature, mass, etc are scalars, and vectors, matrices, relations, tuples, arrays, lists, etc are non-scalars.

> Another representation of a relation has an array for each attribute.

No, this is another description of a relation structure, but a bad description because arrays have order and relations don't.

Regards
  Alfredo Received on Sun Jan 04 2004 - 00:00:51 CET