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A short proof thatN3is not a circle containment order

✍ Scribed by Glenn H. Hurlbert


Publisher
Springer Netherlands
Year
1988
Tongue
English
Weight
100 KB
Volume
5
Category
Article
ISSN
0167-8094

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✦ Synopsis


A partially ordered set P is called a circle containment order provided one can assign to each x e P a circle C x so that x <~ y Β’=~ Cx c_ Cy. We show that the infinite three-dimensional poset N 3 is not a circle containment order and note that it is still unknown whether or not [n] 3 is such an order for arbitrarily large n.


πŸ“œ SIMILAR VOLUMES


[2] x [3] xNis not a circle order
✍ Chiang Lin πŸ“‚ Article πŸ“… 1991 πŸ› Springer Netherlands 🌐 English βš– 233 KB

The result stated in the title is proved in this note. Actually we show that S x N is not a circle order, where S = {( 1, I), (1,2), (1,3), (2, I), (2, 3)}. Furthermore this non-circle order is critical in the sense that (S -{x}) x N is a circle order for any x in S.