non-commutativity in the brain

[Ken Hanly]

My example is not strictly appropriate.
Actually, "is the sister of" is a relation and the property
at issue, being symmetrical rather than commutativity.
However, "is the sister of" is non-symmmetrical (rather than
non-commutative.) Sometimes when x is the sister or y, y is
the sister of x, and sometimes not. If the relation were
symmetrical then if x were the sister of y then y would be
the sister of x.On one interpretation of " x and y are
sisters" it implies that if x is the sister of y then y is
the sister of x since it means that x is a sister of y and y
is a sister of x. That may have been what you were thinking
or alternatively x is the sibling of y is symmetrical.

   Cheers, Ken Hanly

Martin Schiller wrote:
> 
> Ken Hanly said on 4/3/00 8:08 PM
> 
> >I think so: Joan is the sister of John but John is not the
> >sister of Joan.
> >No? Must John be a transsexual?
> 
> Probably a non-commutative experience - or I've forgotten about sex.
> 
> Martin