# What is 2g-precedence?

I am currently reading a couple of papers about event processing. In the context of ordering events, "2g-precedence" is frequently mentioned. I don't know what it is, and I cannot find much information about it. In this paper I was able to find a short explanation that is way over my head, though:

[It is assumed] that the maximum time difference between any two clocks at the same instant of time is bounded by $\delta$. The granularity condition states that the granularity of the global time-base $g$ should not be smaller than $\delta$, $g > \delta$, ensuring that global clocks do not overlap. A global and total order of events can be determined if event timestamps are two or more clock ticks apart, a fact known as 2g-precedence. If this assumption does not hold in all cases, one has to face partial ordering of events.

What is a "granularity condition"? What is a "global time-base"? How do clocks "overlap"? In other words, what is "2g-precedence"?

• You can try reading the original paper ieeexplore.ieee.org/xpl/…, or one of many lecture notes, for example by Verissimo: control.aau.dk/~jdn/edu/courses/litt/nw/verissimo.ps. – Yuval Filmus Sep 15 '15 at 20:00
• 1. Please proof-read your question: you have some spelling errors in there. (Correcting the spelling will help others who might have the same question find it via search.) 2. Can you edit the question to provide a full citation for the paper (title, authors, where published), so that if the link stops working, people can still reconstruct which paper you are referring to? Thank you! – D.W. Sep 15 '15 at 20:11
• This paper may be more related and original. – hengxin Sep 18 '15 at 2:35