function color(graph G, vertex v, color assignment a): if v > n: return True for color in 1,2,3: if color not used by neighbors of v: a[v] = color if color(G, v+1, a): return True a[v] = None return False ( O(3^n \cdot n) ) worst case, but pruning helps in practice. 4. Example on m.3color3 Let m.3color3 be a 5‑vertex graph with edges: (1,2), (1,3), (2,3), (2,4), (3,5), (4,5).
Running backtracking yields a proper 3‑coloring: c(1)=1, c(2)=2, c(3)=3, c(4)=1, c(5)=2. m.3color3
I’ll assume this is a request for a on the 3‑coloring problem (often written as 3-COLOR or 3-COLORABILITY ), with m.3color3 as a placeholder for a model, instance, or exercise identifier. function color(graph G, vertex v, color assignment a):
If that’s correct, here is a concise, ready-to-use paper draft. Author: [Your Name] Date: April 18, 2026 Course/Assignment: m.3color3 Abstract The graph 3‑coloring problem (3‑COLOR) asks whether the vertices of a given graph can be assigned one of three colors such that no two adjacent vertices share the same color. This paper reviews the NP‑completeness of 3‑COLOR, describes a basic backtracking algorithm, and analyzes its complexity. The model m.3color3 is used as a running example to illustrate key concepts. 1. Introduction Let ( G = (V, E) ) be an undirected graph. A proper 3‑coloring is a function ( c: V \to 1,2,3 ) such that for every edge ( u,v \in E ), ( c(u) \neq c(v) ). The decision problem 3‑COLOR is: Given G, does a proper 3‑coloring exist? Author: [Your Name] Date: April 18, 2026 Course/Assignment:
It looks like you’re referencing — possibly a filename, variable name, class name, or assignment ID related to graph theory, algorithms, or complexity theory.