Complex sentence: In number theory, Serre's epsilon conjecture stated a property of Galois representations associated with modular forms which was proven by Ken Ribet in the summer of 1986, in in a significant step towards the proof of Fermat's Last Theorem.
Split into simpler sentences: In number theory, Serre's epsilon conjecture states a property of Galois representations associated with modular forms. This was proven by Ken Ribet in the summer of 1986, in a significant step towards the proof of Fermat's Last Theorem.