Why are some names followed by a four digit number?

Homonymous names are a quite common problem in dblp. You may find papers by at least twenty different persons with the name Chen Li. In these cases, we add some small, unique "mystical" number to make these homonyms distinguishable in the dblp XML format:

<author>Chen Li</author>
<author>Chen Li 0002</author>
<author>Chen Li 0007</author>

This extended name will be used in each record to uniquely identify the specific instance of an author with a given name. Note that 'Chen Li' without a suffix is distinct from all instances with a suffix, say 'Chen Li' or 'Chen Li'.

In the case of homonymous names, dblp aims to use the name version without any suffix as a person disambiguation page, and not as the bibliography of an actual person. Any publication listed on such a page has not been assigned to an actual author (i.e., someone with a homonym suffix number) yet.

However, since in the early days of dblp author name versions without a homonym suffix number had been used as normal bibliography pages, too, there can still be found examples of homonymous names where the entity without any suffix is still considered to model the bibliography of an actual person. Removing the last remnants of these examples by giving explicit suffix numbers is currently a work in progress at dblp.

Currently, you could use the following rule of thumb to distinguish most cases adequately: If a person page has a homonymous name variant using the suffix "0001", and the page carries no additional person information like a home page link or an affiliation note, then this page is most likely just a disambiguation page. Otherwise (e.g., if the earliest homonym name starts with suffix "0002", or there are additional pieces of author information given), then the page is likely to be intended to be the profile of an actual person.

We hope that we will have a much clearer situation in the near future, with no need for such shaky rules.

The four digit number is also part of the URL that leads to the author's page, e.g.

http://dblp.uni-trier.de/pers/hy/l/Li_0007:Chen.html

However, the number is (usually) suppressed when the bibliographic metadata of a paper is printed on a web page, or exported as BibTeX.