Source: wikibot/busemann-s-theorem
= Busemann's theorem
{wiki=Busemann's_theorem}
Busemann's theorem pertains to the theory of hyperbolic geometry, particularly concerning the existence of geodesics and the nature of parallel lines in hyperbolic space. The theorem can often be stated in the context of Busemann functions, which are used to analyze the asymptotic behavior of geodesics in hyperbolic spaces.