%0 Journal Article %T Constructions of commutative automorphic loops %A Premysl Jedlicka %A Michael Kinyon %A Petr Vojtechovsky %J Mathematics %D 2008 %I arXiv %X A loop whose inner mappings are automorphisms is an \emph{automorphic loop} (or \emph{A-loop}). We characterize commutative (A-)loops with middle nucleus of index 2 and solve the isomorphism problem. Using this characterization and certain central extensions based on trilinear forms, we construct several classes of commutative A-loops of order a power of 2. We initiate the classification of commutative A-loops of small orders and also of order $p^3$, where $p$ is a prime. %U http://arxiv.org/abs/0810.2114v2