# Re: The role of logic, & planning ...

```George Levy wrote:

>Marchal wrote:
>
>And we have as results (including the exercices!):
>
> > Any frame (W,R) respects K
> >A frame (W,R) respects T iff  R is reflexive
> >A frame (W,R) respects 4 iff R is transitive
> >A frame (W,R) respects 5 iff R is euclidian
> > (where R is Euclidian means that if xRy and xRz then yRz,  for x, y z
>in W).
> >A frame (W,R) respects D iff (W,R) is ideal
> >A frame (W,R) respects C iff (W,R) is realist.
>
>>We will talk on the semantics of L and Grz later.
>
>I do not think you defined euclidian.... There is obviously a connection
>to geometry but I dn't see it.```
```
I just have defined it above.
R is Euclidian means that if xRy and xRz then yRz.
A more concrete "euclidian" relation: W = the plane, i.e. the worlds are
the
point of the plane. xRy = there is a straight line from x to y.
It is clearly euclidian because if there is a straight line from x to y,
and
straight line from x to z, there is a straight line from y to z.

You can forget it because 5 is the only formula we will never meet.

>I guess we have to visit the whole Louvre to get to the Mona Lisa :-).
>Any
>short cut?

Thanks for "Mona Lisa" !.
A short cut? Gosh! My machine interview *is* a terrible short cut :-)
Well I will try to follow a spirale, not giving you all
technical details (at once).
Don't forget we are going from "the" psychology of the machines, *by* the
machines (and by their angels!) to their "most probable physical
beliefs".
So there is some need to be cautious with the vocabulary, to say the
least.

Bruno

```