%0 Journal Article %T Permutation orbifolds and their applications %A P. Bantay %J Physics %D 2001 %I arXiv %X The theory of permutation orbifolds is reviewed and applied to the study of symmetric product orbifolds and the congruence subgroup problem. The issue of discrete torsion, the combinatorics of symmetric products, the Galois action and questions related to the classification of RCFTs are also discussed. %U http://arxiv.org/abs/hep-th/0104203v1