Breidbart Index

The Breidbart Index, developed by Seth Breidbart, is the most significant cancel index in Usenet.

A cancel index measures the dissemination intensity of substantively identical articles. If the index exceeds a threshold the articles are called newsgroup spam. They can then be removed using third party cancel controls.

The principal idea of the Breidbart-Index is to give these methods different weight. With a crossposted message less data needs to be transferred and stored. And excessive crossposts (ECP) are also a likely beginner's error, while excessive multiposts (EMP) suggest deliberate usage of special software.

The crucial issue is categorizing multiple articles as substantively identical. This includes

The Breidbart Index of a set of articles is defined as the sum of the square root of n, where n is the number of newsgroups to which an article is cross posted.

${\displaystyle {\mbox{BI}}=\sum _{k=1}^{m}{\sqrt {n_{k}}}}$

Two copies of a posting are made, one to 9 groups, and one to 16.

${\displaystyle {\sqrt {9}}+{\sqrt {16}}=3+4=7}$

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