This paper deals with a generalization of the following simple observation. Suppose there are distinct elements a, b of the chain complete poset (P, <) such that P( < a) C P( < b) and P( > a) L P( > h); if P( < a) and P( > a) are both fixed point free (fpf), then P is also fpf (we say P is trivially
The ANTI-order and the fixed point property for caccc posets
β Scribed by Boyu Li; E.C. Milner
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 670 KB
- Volume
- 175
- Category
- Article
- ISSN
- 0012-365X
No coin nor oath required. For personal study only.
β¦ Synopsis
This paper settles a conjecture made in (Li [2]) that, if (PC: ~ ~< 2) is an ANTI-perfect sequence in a connected caccc poset having no one-way infinite fence, then either there are ~ < 2 and x e Pe~+l such that Pc(> x) and P~(<x) are both fixed point free (fpf), in which case P is also fpf, or P has the fixed point property (fpp) if and only if P;, has the fpp.
π SIMILAR VOLUMES
In Part I we defined the ANTI-order, ANTI-good subsets, ANTI-perfect sequences and ANTIcores for caccc posets. In this part we prove the main result: If n = (P. : < < 2.) is an ANTIperfect sequence of a connected caccc poset P which dots not contain a one-way infinite fence, then PC is a retract of
A strengthened form of the fixed point property for posets is presented, in which isotone functions are replaced by more general isotone relations. For finite posets, this 'relational fixed point property' turns out to be equivalent to dismantlability. But an example shows that not every infinite po
It has been an open problem to characterize posets P with the property that every order-preserving map on P has a fixed point. We give a characterization of such posets in terms of their retracts.