A Local Proof of Langlands's First Main Lemma for Local Epsilon Factors over Nonarchimedean Local Fields

We give a complete local proof of Langlands's First Main Lemma for local epsilon factors over nonarchimedean local fields. The proof builds on Dwork's $p$-adic calculations and Langlands's formulation of the local method. The present paper reformulates these calculations in a common normalization an