  While symmetries are well understood for Boolean formulas and successfully
exploited in practical SAT solving, less is known about symmetries in
quantified Boolean formulas (QBF). There are some works introducing adaptions
of propositional symmetry breaking techniques, with a theory covering only very
specific parts of QBF symmetries. We present a general framework that gives a
concise characterization of symmetries of QBF. Our framework naturally
incorporates the duality of universal and existential symmetries resulting in a
general basis for QBF symmetry breaking.
