THE SOLID TRANSPORTATION PROBLEM
L INEAR PROGRAMMING problems are similar in that they all require that a linear function of a set of variables is optimized while the variables themselves satisfy a number of linear constraints. All problems of this type can be solved by the use of DANTZIG'S Simplex method. II A number of alternative methods have been constructed for special types of problems. The most useful have probably been those of the transportation type. The original work in this field was by G. B. Dantzig,t[I but the method more usually employed is a refinement of this called the modi method. 23' An extension of the transportation type of problem was stated by E. SCHELL[41 and may be thought of as a block in which the layers in all directions form restricted transportation problems. This paper describes the adaptation of the modi method to solve this extended problem