# [sc34wg3] Tau: The role in operator

**Robert Barta
**
sc34wg3@isotopicmaps.org

*Sun, 1 Aug 2004 21:33:11 +1000*

On Sat, Jul 31, 2004 at 07:00:04PM -0400, Lars Marius Garshol wrote:
>* When going through the Tau model at the RM workshop today we found one
*>* strange thing that we couldn't quite account for.
*>*
*>* The role in operator is defined as
*>*
*>* a upm r = ...
*...
>* We discussed this at the RM workshop when Ann presented the model and
*>* agreed that there are two possible interpretations:
*>*
*>* 1) m up r = {a | a element-of m ^ exists p | <r, p> element-of a}
*>*
*>* 2) m up <r, p> = {a | a element-of m ^ <r, p> element-of a}
*>*
*>*
*>* Did we miss something, or is there a problem with the notation here?
*>* Also, which of the two interpretations is the intended one?
*
Lars (et.al),
This is clearly a typo. It should read
p -> r = {a element-of m | exists p : <r, p> element-of a}
It basically delivers ALL assertions in the map where p is a player of
the role r.
\rho