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In 2009, the US House of Representatives agreed to a resolution designating March 14 as “Pi Day”.

So I thought I’d see whether I could rustle up a nice example of pi in the Code of Federal Regulations. I did manage to find the π I was looking for, but it turns out that pi also gives us some examples of why we need to disambiguate.

In the process I also found:

So the story of “pi” in the CFR is a story of disambiguation. When we read (or our software parses) the original text of a particular regulation, it’s reasonably straightforward to tell which of the many “pi”s it’s discussing. We have capitalization, punctuation, formatting, and structural and contextual clues. Once the search engines work their case-folding, acronym normalization, and other magic, we end up with an awful lot of “pi”s and very little context.

Postscript. The real pi was a bit of a letdown: “P = pi (3.14)” – well, close enough.