quiz no- 5

What is the difference between minimal cost network flows and transportation

problems?

• The minimal cost network flows are special cases of transportation problems

• The transportation problems are special cases of the minimal cost network flows

• There is no difference

• The transportation problems are formulated in terms of tableaus, while the minimal

  cost network flows are formulated in terms of graphs

With the transportation technique, the initial solution can be generated in any fashion

one chooses. The only restriction is that

• the edge constraints for supply and demand are satisfied.

• the solution is not degenerate.

• the solution must be optimal.

• one must use the northwest-corner method.

The purpose of the stepping-stone method is to

• develop the initial solution to the transportation problem.

• assist one in moving from an initial feasible solution to the optimal solution.

• determine whether a given solution is feasible or not.

• identify the relevant costs in a transportation problem.

The purpose of a dummy source or dummy destination in a transportation problem is

to

• prevent the solution from becoming degenerate.

• obtain a balance between total supply and total demand.

• make certain that the total cost does not exceed some specified figure.

• provide a means of representing a dummy problem.

Which of the following is NOT needed to use the transportation model?

• the cost of shipping one unit from each origin to each destination

• the destination points and the demand per period at each

• the origin points and the capacity or supply per period at each

• degeneracy

Which of the following is a method for improving an initial solution in a

transportation problem?

• northwest-corner

• intuitive lowest-cost

• southeast-corner rule

• stepping-stone

The transportation method assumes that

• there are no economies of scale if large quantities are shipped from one source to

  one destination.

• the number of occupied squares in any solution must be equal to the number of rows

  in the table plus the number of columns in the table plus 1.

• there is only one optimal solution for each problem.

• the number of dummy sources equals the number of dummy destinations.

Which of these statements about the stepping-stone method is best?

• A dummy source and destination must be added if the number of rows plus columns

  minus 1 is not equal to the number of filled squares.

• Only squares containing assigned shipments can be used to trace a path back to

  an empty square.

• An improvement index that is a net positive means that the initial solution can be

  improved.

• Only empty squares can be used to trace a path back to a square containing an

  assigned shipment

In a transportation problem, we must make the number of __________ and

__________ equal.

• destinations; sources

• units supplied; units demanded

• columns; rows

• positive cost coefficients; negative cost coefficients

• warehouses; suppliers

__________ or __________ are used to "balance" an assignment or transportation

problem.

• Destinations; sources

• Units supplied; units demanded

• Dummy rows; dummy columns

• Large cost coefficients; small cost coefficients