A short proof of the degree bound for interval number

Abstract A short proof is given of the fact that every graph has an interval representation of depth 2 in which each vertex v is represented by at most ⌊ 1 2 (d(v)+1)⌋ intervals, except for an arbitrarily specified vertex w that appears left-most in the representation and is represented by at most ⌈ 1 2 ;(d(w)+1)⌉ intervals.