Orbifold $eta$-invariants C. Farsi 58G0358G10orbifoldEta invariantgeneralized Atiyah-Singer Theorem In this paper we generalize the classical Atiayh-Patodi-Singer Theorem to orbifolds. From this result, it follows that orbifold $\eta$-invariants can be classically defined. Indiana University Mathematics Journal 2007 text pdf 10.1512/iumj.2007.56.2959 10.1512/iumj.2007.56.2959 en Indiana Univ. Math. J. 56 (2007) 501 - 522 state-of-the-art mathematics http://iumj.org/access/