Burnside's lemma
lemma stating that, given a finite group G acting on a set, the number of orbits times |G| equals the sum (over every element of G) of the numbers of fixed points
en-GB/bɜːnsaɪdz ˈlɛmə/
en-US/ˈbɝnˌsaɪdz ˈlɛmə/
lemma stating that, given a finite group G acting on a set, the number of orbits times |G| equals the sum (over every element of G) of the numbers of fixed points