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1. • CommentRowNumber1.
   • CommentAuthorUrs
   • CommentTimeJan 4th 2018
   • PermaLink
   Author: Urs
   Format: MarkdownItexat _[[S-matrix]]_ and elsewhere is reference to the "[[causal order]]"-relation, the relation saying that for a pair $(S_1,S_2)$ of subsets of a spacetime, $S_1$ does not intersect the past of $S_2$, or equivalently that $S_2$ does not intersect the future of $S_1$. (Following a suggestion by Arnold Neumaier, a neat suggestive notation for this is $S_1 {\vee\!\!\!\wedge} S_2$, which I have been implementing now at _[[S-matrix]]_.) I am starting to give this concept its own entry, currently titled "[[causal order]]"; but what's good terminology? This relation ${\vee\!\!\!\wedge}$ is not really an [[ordering]], since it is not transitive. It would seem tempting to say "causal relation", but googling for this term shows that has an different established meaning.

   at S-matrix and elsewhere is reference to the “causal order“-relation, the relation saying that for a pair $(S_1,S_2)$ of subsets of a spacetime, $S_1$ does not intersect the past of $S_2$, or equivalently that $S_2$ does not intersect the future of $S_1$.

   (Following a suggestion by Arnold Neumaier, a neat suggestive notation for this is $S_1 {\vee\!\!\!\wedge} S_2$, which I have been implementing now at S-matrix.)

   I am starting to give this concept its own entry, currently titled “causal order”; but what’s good terminology?

   This relation ${\vee\!\!\!\wedge}$ is not really an ordering, since it is not transitive. It would seem tempting to say “causal relation”, but googling for this term shows that has an different established meaning.