TURKISH JOURNAL OF MATHEMATICS, vol.43, no.3, pp.1770-1775, 2019 (Journal Indexed in SCI)
Article / Article
Title of Journal :
TURKISH JOURNAL OF MATHEMATICS
We study the involution of the real line, induced by Dyer's outer automorphism of PGL(2,Z). It is continuous at irrationals with jump discontinuities at rationals. We prove that its derivative exists almost everywhere and vanishes almost everywhere.