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Published byRamon Piller Modified over 2 years ago

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Transportation problem Factories Customers Requirement for goods Production capacity... Minimum cost of transportation satisfying the demand of customers. aiai aiai bjbj bjbj i-th factory delivers to j-th customer at cost c ij a1a1 a2a2 anan bmbm b1b1 b2b2

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Transportation tableau 7 x 11 3 x 12 4 x 13 u18u18 4 x 21 2 x 22 2 x 23 u26u26 2 x 31 1 x 32 5 x 33 u33u33 v14v14 v22v22 v33v33 cost c ij of delivering from ith factory to jth customer supply a i of ith factory demand b j of jth customer shadow customer’s “price” shadow factory “price” shadow prices are relative to some baseline amount transported

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Transportation problem a1a1 b1b1 a2a2 b2b2 b3b3 a3a3 a4a4 b4b4 7 x 11 3 x 12 4 x 13 u18u18 4 x 21 2 x 22 2 x 23 u26u26 2 x 31 1 x 32 5 x 33 u33u33 v14v14 v22v22 v33v33 7 x 11 3 x 12 4 x 13 0 x 14 u18u18 4 x 21 2 x 22 2 x 23 0 x 24 u26u26 2 x 31 1 x 32 5 x 33 0 x 34 u33u33 v14v14 v22v22 v33v33 v48v48 7 x 11 3 x 12 4 x 13 0 x 14 u18u18 4 x 21 2 x 22 2 x 23 0 x 24 u26u26 2 x 31 1 x 32 5 x 33 0 x 34 u33u33 9 x 41 8 x 42 11 x 43 0 x 44 u40u40 v14v14 v22v22 v33v33 v48v48

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7 x 11 3 x 12 4 x 13 0 x 14 u18u18 4 x 21 2 x 22 2 x 23 0 x 24 u26u26 2 x 31 1 x 32 5 x 33 0 x 34 u33u33 v14v14 v22v22 v33v33 v48v48 Transportation Simplex Applying the Simplex method to the problem Basic solution – min-cost method Pivoting – shadow prices set u 1 = 0, then u i + v j =c ij – reduced cost pivot if u i + v j > c ij Finding a loop 0 2 0 6 take the smaller of the two 2 6 0 1 0 3 12 0 33 0 0 must mark exactly m + n – 1 = 6 cells cost = 3×7 + 3×4 + 2×0 + 1×2 + 2×1 + 6×0 = 37 z = 37

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7 x 11 3 x 12 4 x 13 0 x 14 u18u18 4 x 21 2 x 22 2 x 23 0 x 24 u26u26 2 x 31 1 x 32 5 x 33 0 x 34 u33u33 v14v14 v22v22 v33v33 v48v48 Transportation Simplex Applying the Simplex method to the problem Basic solution – min-cost method Pivoting – shadow prices set u 1 = 0, then u i + v j =c ij – reduced cost pivot if u i + v j > c ij Finding a loop 6 2 12 33 z = 37 0 4 u i =0 and v j must sum up to c ij = 4v j = 4 7 0 -5 6 0

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7 x 11 3 x 12 4 x 13 0 x 14 u18u18 4 x 21 2 x 22 2 x 23 0 x 24 u26u26 2 x 31 1 x 32 5 x 33 0 x 34 u33u33 v14v14 v22v22 v33v33 v48v48 Transportation Simplex Applying the Simplex method to the problem Basic solution – min-cost method Pivoting – shadow prices set u 1 = 0, then u i + v j =c ij – reduced cost pivot if u i + v j > c ij Finding a loop 6 2 12 33 z = 37 0 47 0 -5 6 0 calculate u i + v j -5 76 4 6 > > > > ≤ ≤

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7 x 11 3 x 12 4 x 13 0 x 14 u18u18 4 x 21 2 x 22 2 x 23 0 x 24 u26u26 2 x 31 1 x 32 5 x 33 0 x 34 u33u33 v14v14 v22v22 v33v33 v48v48 Transportation Simplex Applying the Simplex method to the problem Basic solution – min-cost method Pivoting – shadow prices set u 1 = 0, then u i + v j =c ij – reduced cost pivot if u i + v j > c ij Finding a loop New basis 6 2 2+Δ2+Δ 11+Δ1+Δ 22-Δ2-Δ 33-Δ3-Δ 3 z = 37 0 47 0 -5 6 0 -5 76 4 6 > > > > ≤ ≤ +Δ+Δ 6-Δ6-Δ Largest feasible Δ = 2 2 4 4 1 3 z = 29

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