A pregroup is a partially ordered monoid in which every element has a left and a right adjoint. The main result is that for some well-behaved subgroups of the group of diffeomorphisms of the real numbers, the set of all endofunctions of the integers that are asymptotic at $\pm\infty$ to (the restriction to the integers of) a function in the subgroup is a pregroup.
Keywords: subpregroups of the Lambek pregroup
2000 MSC: 91F20, 18B35
Theory and Applications of Categories,
Vol. 12, 2004,
No. 8, pp 262-269.
http://www.tac.mta.ca/tac/volumes/12/8/12-08.dvi
http://www.tac.mta.ca/tac/volumes/12/8/12-08.ps
http://www.tac.mta.ca/tac/volumes/12/8/12-08.pdf
ftp://ftp.tac.mta.ca/pub/tac/html/volumes/12/8/12-08.dvi
ftp://ftp.tac.mta.ca/pub/tac/html/volumes/12/8/12-08.ps