Diffeomorphism groups of critical regularity
Diffeomorphism groups of critical regularity
Abstract Let M be a circle or a compact interval, and let $$\alpha =k+\tau \ge 1$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>α</mml:mi> <mml:mo>=</mml:mo> <mml:mi>k</mml:mi> <mml:mo>+</mml:mo> <mml:mi>τ</mml:mi> <mml:mo>≥</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> be a real number such that $$k=\lfloor \alpha \rfloor $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>k</mml:mi> <mml:mo>=</mml:mo> <mml:mo>⌊</mml:mo> <mml:mi>α</mml:mi> <mml:mo>⌋</mml:mo> </mml:mrow> </mml:math> . We …