关于时空因果序中反链的注记
Remarks on antichains in the causality order of space-time
摘要：
这两个密切相关的洛伦兹不变的时空偏序的反链割集的存在和分级的可能性进行了区分。有质量粒子和无质量粒子的世界线是时空因果序中的最大链，反链割集是因果偏序中各种等级的层次。较弱的次腔因果序的最大链不需要拓扑连接，次腔因果没有反链割集，不能分级。光学线和超平面，分离线，惯性平面和线的组合特征，最终在因果顺序方面产生亚历山德罗夫-塞曼定理的简单证明。
英文摘要：
The two closely related Lorentz-invariant partial orders of space-time are distinguished with respect to the existence of antichain cutsets and the possibility of grading. World lines of particles with or without mass are the maximal chains in the causality order of space-time, and antichain cutsets are the levels of the various gradings of the causality partial order. The maximal chains of the weaker, subluminal causality order need not be connected topologically, subluminal causality has no antichain cutsets and cannot be graded. Combinatorial characterizations of optical lines and hyperplanes, separation lines, inertia planes and lines, ultimately in terms of the causality order yield a simple proof of the Alexandrov-Zeeman Theorem.
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