You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: The Forwarding Indices of Graphs -- a Survey 
Chapter Title:  Problems and Trivial Cases 
1. Abstract of Cited Paper (BIB001):  For a given graph G of order n, a routing R is a set of n(n − 1) elementary paths specified for every ordered pair of vertices in G. The edge forwarding index of a network (G,R), denoted π(G,R) is the maximum number of paths of R going through any edge e of G. The edge forwarding index of G, denoted π(G), is the minimum of π(G,R) taken over all the possible routings R of G. Given n ≤ 15 and Δ ≤ n − 1 we determine πΔ,n, the minimum of π(G) taken over all graphs G of order n with maximum degree at most Δ. This is known as the edge forwarding index problem. © 1993 by John Wiley & Sons, Inc.

Literature Review:
Problem 4.1 (Chung et al BIB001 ) Given ∆ ≥ 2 and n ≥ 4, determine ξ ∆,n , and exhibit an (n, ∆)-graph G and R of G for which ξ(G, R) = ξ ∆,n . BIB002 ) Given ∆ ≥ 2 and n ≥ 4, determine π ∆,n , and exhibit an (n, ∆)-graph G and R of G for which π(G, R) = π ∆,n .