The ghost of an index theorem

Robin Harte
1989 Proceedings of the American Mathematical Society  
The "index theorem" whose spirit we invoke says that the index of a product of Fredholm operators is the sum of their indexes; our extension is to operators with "generalized inverses".
doi:10.1090/s0002-9939-1989-0975646-8 fatcat:dkof2c5tlfdwriavsjtm2wq6bm