From The Free On-line Dictionary of Computing (19 January 2023):
PI
<programming> An interface between Prolog application
programs and the X Window System that aims to be independent
from the Prolog engine, provided that it has a Quintus
foreign function interface (e.g. SICStus and YAP). PI is
mostly written in Prolog and is divided in two libraries: Edipo
- the lower level interface to the Xlib functions; and Ytoolkit
- the higher level user interface toolkit.
(ftp://ftp.ncc.up.pt/pub/prolog/ytoolkit.tar.Z).
E-mail: Ze' Paulo Leal <zp@ncc.up.pt>.
(1993-03-02)
From The Free On-line Dictionary of Computing (19 January 2023):
pi
1. <character> The greek lower-case letter P.
2. <mathematics> The mathematical constant that is the
circumference of a circle divided by its diameter. Pi is written
as the greek character pi.
Some have suggested that pi is the wrong choice and a better
constant to describe the geometry of circles would have been 2*pi,
for which they have proposed the name tau. Most practising
mathematicians think this is silly. The xkcd comic strip
proposed (http://xkcd.com/1292/) a compromise between pi and
tau, namely 1.5*pi or "pau".
(2013-12-09)