[1]

C. Berge,*Graphs and Hypergraphs* (Dunod, Paris, 1970).

[2]

E. Balas, “Facets of the knapsack polytope,”*Mathematical Programming* 8 (1975) 146–164.

[3a]

E. Balas and E. Zemel, “Critical cutsets of graphs and canonical facets of set packing polytopes,”*Mathematics of Operations Research* (1977) 15–19.

[3b]

E. Balas and E. Zemel, “Facets of the knapsack polytope from minimal covers,”*SIAM Journal of Applied Mathematics* 34 (1978) 119–148.

[4]

V. Chvátal, “On certain polytopes associated with graphs,”*Journal of Combinatorial Theory (B)* 18 (1975) 138–154.

[5]

M. Conforti and M. Laurent, “On the facial structure of independence system polyhedra,”*Mathematics of Operations Research*, to appear.

[6]

G. Cornuéjols and A. Sassano, “On the 0, 1 facets of the set covering polytope,”*Mathematical Programming* 43 (1989) 45–55.

[7]

J. Edmonds, “Matroids and the greedy algorithm,”*Mathematical Programming* 1 (1971) 127–136.

[8]

J. Edmonds, “Matroid intersection,”*Annals of Discrete Mathematics 4* (1979) 39–49.

[9]

R. Euler, M. Junger and G. Reinelt, “Generalizations of cliques, odd cycles and anticycles and their relation to independence system polyhedra,” preprint, University of Augsburg.

[10]

R. Giles, “Submodular functions, graphs and integer polyhedra,” Ph.D. thesis, University of Waterloo (1975).

[11]

G.L. Nemhauser and L.E. Trotter, “Properties of vertex packing and independence system polyhedra,”*Mathematical Programming* 6 (1974) 48–61.

[12]

M.W. Padberg, “On the facial structure of set packing polyhedra,”*Mathematical Programming* 5 (1973) 199–215.

[13]

M.W. Padberg, “A note on zero–one programming,”*Operations Research* 23 (1975) 833–837.

[14]

A. Sassano, “On the facial structure of the set covering polytope,”*Mathematical Programming*, to appear.

[15]

Y. Sekiguchi, “A note on node packing problems on hypergraphs,”*Operations Research Letters* 2(5) (1983) 243–247.

[16]

L.E. Trotter, “A class of facet producing graphs for vertex packing polyhedra,”*Discrete Mathematics* 12 (1975) 373–388.

[17]

D. Welsh,*Matroid Theory* (Academic Press, New York, 1976).