Feb 16, 2021
_What is a Lefschetz pencil?_ by Robert Gompf
#pencil#algebraic geometry#Dehn twist#Max Dehn#Kirby calculus#Robion Kirby#Solomon Lefschetz#C#manifolds#surgery#topology#mathematics#maths#math#blowing up#blow-up#CP2#complex projective plane#projective geometry#singularity#singularities#fibrations#genus#surfaces#excision#4-manifolds#bundles#monodromy#cylinder#torus