Q: In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
In the " Prose Edda " book " Gylfaginning " , Elli defeats Thor in a wrestling match .
A:
In Norse mythology ( a subset of Germanic mythology ) , Elli ( Old Norse " old age " ) is a personification of old age who , in the " Prose Edda " book " Gylfaginning " , defeats Thor in a wrestling match .