Sophus Lie, a giant in mathematics ; Felix Klein, his life and mathematics / Lizhen Li -- Klein and the Erlangen Programme / Jeremy J. Gray -- Klein's "Erlanger Programm" : do traces of it exist in physical theories? / Hubert Goenner -- On Klein's so-called non-Euclidean geometry / Norbert A 'Campo, Athanase Papadopoulos -- What are symmetries of PDEs and what are PDEs themselves? / Alexandre Vinogradov -- Transformation groups in non-Riemannian geometry / Charles Frances -- Transitional geometry / Norbert A 'Campo, Athanase Papadopoulos -- On the projective geometry of constant curvature spaces / Athanase Papadopoulos, Sumio Yamada -- The Erlangen program and discrete differential geometry / Yuri B. Suris -- Three-dimensional gravity--an application of Felix Klein's ideas in physics / Catherine Meusburger -- Invariances in physics and group theory / Jean-Bernard Zuber. |