Identity is the basis
of logic... like it or not.
This page was last updated 1/27/2003 by Seth Russell to include the link
below to Tim Berners-Lee's paper below.
I like it. However, I am troubled by the logical purity of
the concept. It seems to me that the concept of identity can never
be exactly expressed in any one dimensional language and that most
logical languages including 2nd order predicate calculus are one
dimensional in this sense. For example A == B (where == stands for
"identical-to" ) must always be a lie, because the symbol on the left
of the copula is named A and the symbol on the right of the copula is
named B, therefore the two symbols are not identical.
Now, representing identity to this level of quibble in SVO (Subject
Verb Object) is not a problem. In the diagram
the two unnamed symbols are identical iff there is a one to one
correspondence between every R1 and R2 and every S1 and S2, U
representing every other symbol in the universe.
For a more on SVO type Knowledge Representation see Mentography
Primer
For more about identity on the Semantic Web see: