1. Introduction  
2. Eigenfunctions in combinatorial configurations and MS-problem  
2.1. Equitable partitions and 1-perfect codes  
2.2. $T(k-1, k, v)$ Steiner trades  
3. Basic definitions  
4. Weight Distribution Bound  
5. Hamming graph  
6. Doob graph  
7. Johnson graph  
8. Grassmann Graph  
9. Bilinear Forms Graph  
10. Paley graph  
11. The Star graph  
12. Some remarks on optimal eigenfunctions of graphs  
13. Open problems