A Poincaré–Hopf theorem in the spirit of Pugh is proven for compact orbifolds with
boundary. The theorem relates the index sum of a smooth vector field in
generic contact with the boundary orbifold to the Euler–Satake characteristic
of the orbifold and a boundary term. The boundary term is expressed as
a sum of Euler characteristics of tangency and exit-region orbifolds. As a
corollary, we express the index sum of the vector field induced on the inertia
orbifold to the Euler characteristics of the associated underlying topological
spaces.
Keywords
orbifold, orbifold with boundary, Euler–Satake
characteristic, Poincare–Hopf theorem, vector field, vector
field index, Morse index, orbifold double