Bruno Marchal wrote:
What could this mean in a real world example?
Take W as the set of places in Brussels. Take R to be "accessible by
walking in a finite number of foot steps". Then each places at Brussels
is accessible from itself, giving that you can access it with zero
steps, or two steps (forward, backward, ...).
Take W as the set of humans, say that aRb if a can see directly, without
mirror, the back of b. Then a can access all humans except themselves. R
is said to be irreflexive.
Another important "concrete" example, which will help us latter to study
the modal logic of quantum logic. Take the worlds to be the vector of an
Hilbert Space (or of the simpler 3-dimensional euclidian space). Say
that a is accessible to b, i.e. aRb, if the scalar product of a and b
is non null (i.e. a and b are not orthogonal).
These are good illustrative examples, but how do they apply to worlds that just
consist of propositions? What is the relation of accessibility in the p,q,r
world(s)? Is it negation?
- Re: Quantum Immortality and Information Flow (was off-list) Brent Meeker