non-commutativity in the brain

Ken Hanly khanly at
Tue Apr 4 11:33:41 PDT 2000

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

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