1. 数理計画法:Mathematical Programming(最適化問題:Optimization) 目的関数 Objective function: 制約条件式 Constraints function(s): Z(x1,x2,…,xn) b1(x1,x2,…,xn)=0 ….. bm1(x1,x2,…,xn)=0 bm1+1(x1,x2,…,xn)≦0 ….. bm1+m2 (x1,x2,…,xn)≦0 独立変数:Dependent variable: 従属変数:Independent variable: Z(x1,x2,…,xn) x1,x2,…,xn 数理計画法 Discrete Variable < Continuous Variable (differentiable) Constrained < Unconstrained Linear Function > Non Linear Function > Probabilistic Deterministic ・・・・・・・・・・ ・・・・・・・・・ 1. Linear Programming * Linear Programming * Integer Linear Programming 3. Combinational Optimization * Dynamic Programming * Relaxation Method * Branch and Bound Method 2. Non Linear Programming * Unconstrained Optimization * Constrained Optimization 4. Probabilistic Methods * Queuing Theory * Game Theory * Markov Chains 2.1 線形計画法:Linear Programming Min. Z(xi) = Σ ai・ xi x2 s.t. Σb1i ・ xi ≦ b01 …… Σbmi ・ xi ≦ b0m x1 輸送問題:Transport Problem 輸送問題: Transport Problem 輸送問題: Transport Problem 目的関数 Min. Σ Σ Cij・ xij 制約条件 xij [ton] Cij [B/ton] Si [ton] Cj [ton] s.t. Σ xij ≦ Si [ton] Σ xij >= Cj [ton] : i倉庫 からj 百貨店への輸送荷物量 : i倉庫 から j 百貨店への単位重量あたり輸送コスト : i倉庫における在庫量 : j 百貨店における消費量 線形計画問題の条件 1. 2. 3. 目的関数とすべての制約が線形関数 制約条件はすべて ≦, ≧, or = 変数は連続変数 c.f.整数計画法 線形計画法の解法 1. 図形解法 2. 代数解法 3. シンプレックス法 [例] Max. Z=60x1+80x2 s.t. x1 + x2≦10 4x1+6x2≦48 0≦x1, 0≦x2 2.1.1図形解法 (1) x2 x1 +x2≦10 10 x1 +x2=10 8 4x1+6x2=48 4x1+6x2≦48 x1 = 0 0≦ x1 0≦ x2 x2 = 0 Feasible Region 0 0 10 12 x1 図形解法(2) x2 Z ( Z Z , ) x y Z=60x1+80x2 10 x2=-3/4x1+Z/80 8 x1 +x2=10 4x1+6x2=48 =(3,4) Feasible Region 0 0 x2=-3/4x1+Z4/80 x2=-3/4x1+Z3/80 x2=-3/4x1+Z2/80 x2=-3/4x1+Z1/80 x1 =6 x2 =4 Z =680 端点:Corner Point(1) x2 実行可能領域 Feasible Region 制約条件を全て満たす点の集合 10 8 (6,4) Feasible Region 0 0 Corner Point 10 12 x1 端点(2) x1 1-t x1 x2 x3=tx1+(1-t)x2 S : Convex Set For all t [0,1] and all x1,x2 S : Convex Set* t x2 端点(3) 端点定理 線形計画問題の最適解は,端点で得られる もし,端点以外で,最適解が得られるとすると, x0 =αx1+βx2 α+β = 1 α≧0,β≧0 Z = f(x0) = cx0 = cαx1+cβx2 = αf(x1)+βf(x2) = α(f(x1)−f(x2))+f(x2) = β(f(x2)−(x1))+f(x1) If f(x1)≦f(x2) then f(x1)≦f(x0)≦f(x2) If f(x2)≦f(x1) then f(x2)≦f(x0)≦f(x1) In either case, f(x0) is not a optimal solution. 端点(4) a11x1+a21x2=0 a12x1+a22x2=0 a11x1+a21x2 + a31x3=0 a12x1+a22x2 + a32x3 =0 a13x1+a23x2 + a33x3 =0 凸領域 x1 x1 x2 x2 x3=tx1+(1-t)x2 S For all t [0,1] and all x1,x2 S x3= tx1+ (1- t)x2 S For all x1,x2 S 2.2.2 代数解法 スラック変数 Slack Variable : x3, x4 Z=60x1+80x2 s.t. x1 + x2≦10 4x1+6x2≦48 0≦x1, 0≦x2 Z=60x1+80x2 s.t. x1 + x2 +x3 4x1+6x2 = 10 +x4 =48 0≦x1, 0≦x2 , 0≦x3 , 0≦x4 (x1 , x2 , x3 , x4 ) x2 x1 +x2=10 (0,10,0,-12) 4x1+6x2=48 10 8 x1 = 0 (0,8,2,0) x2 = 0 (6, 4, 0, 0) (12, 0,-2, 0) 0 0 12 10 (0, 0,10,48) (10, 0, 0,8) x1 + x2 +x3 4x1+6x2 = 10 +x4 =48 x1 標準系 a11x1 + a12x2 + ‥‥ + a1nxn+xn+1 a21x1 + a22x2 + ‥‥ + a2nxn ‥‥ ‥‥ am1x1 + am2x2 + ‥‥ xi= 0 xj = 0 ‥ xk=0 + amnxn n 非基底解 :Non-Basic Solutions 非基底変数:Non-Basic Variables = b1 +xn+2 = b2 +xn+m = bm xi’= c1 xj’= c2 ‥ xk’=cm m 基底解 : Basic Solutions 基底変数 : Basic Variables ① ② ③ ④ ⑤ ⑥ X1 X2 X3 X4 0 0 10 48 0 10 0 -12 0 8 2 0 10 0 0 8 12 0 -2 0 6 4 0 0 x2 ② Z 0 800 x1 + x2 +x3 640 600 4x1+6x2 680 10 8 (0,8,2,0) ③ ① (6, 4, 0, 0) ⑥ 0 0 (0, 0,10,48) +x4 =48 720 (0,10,0,-12) ④10 (10, 0, 0,8) 非基底変数 xi =0 基底変数 xi =c=0 (12, 0,-2, 0) ⑤ 12 x1 = 10 2.2.3 シンプレックス法 Simplex Method シンプレックス法の概念 Z(x15,x25,x35) Z Z(x12,x22,x32) Z(x11,x21,x31) 隣接端点(1) a11x1+a12x2+a13x3-b1=0 (1) (2) a21x1+a22x2+a23x3-b2=0 (3) a31x1+a32x2+a33x3-b3=0 (4) a41x1+a42x2+a43x3-b1 =0 a21x1+a22x2+a23x3-b2=0 a31x1+a32x2+a33x3-b3=0 a41x1+a42x2+a43x3-b1 =0 a11x1+a12x2+a13x3-b1=0 a21x1+a22x2+a23x3-b2=0 a31x1+a32x2+a33x3-b3=0 隣接端点(2) (1) a21x1+a22x2+a23x3+x4 =b2 (2) a21x1+a22x2+a23x3 + x5 =b2 (3) a31x1+a32x2+a33x3 +x6 =b3 (4) a41x1+a42x2+a43x3 +x7 =b4 a21x1+a22x2+a23x3-b2=0 Basic Non-Basic Variables Variables x1=a1 x2=a2 x3=a3 x4=a4 Basic Non-Basic Variables Variables x1=c1 x2=c2 x3=c3 x5=0 x6=0 x7=0 x4=0 x5=0 x6=0 x7= c7 (1) (2) (3) (4) 隣接端点(3) n dimensions * the number of non-basic variables at the corner points is n. * n-1 non-basic variables are common between the adjacent corner point x2 x1 + x2 +x3 4x1+6x2 = 10 10 8 ⑥ +x4 =48 Non-Basic Variables xi =0 Basic Variables xi =c=0 (6, 4, 0, 0) ① 0 0 (0, 0,10,48) ④10 (10, 0, 0,8) 12 x1 隣接端点(4) a11x1 + a12x2 + ‥‥ + a1nxn +xn+1 a21x1 + a22x2 + ‥‥ + a2nxn ‥‥ ‥‥ am1x1 + am2x2 + ‥‥ + amnxn Non-Basic Variables = b1 (1) = b2 (2) +xn+2 +xn+m = bm (m) Basic Variables xn+2 → Non-Basic Variables, x1 → Basic Variables x1 + a12’x2 + ‥‥ + a1n’xn + xn+1 + a1n’xn+2 = b1 ’ (1) ’ a22’x2 + ‥‥+ a2n’xn + a1n’xn+2 = b2 ’ (2) ’ ‥‥ ‥‥ am2’x2 + ‥‥+amn’xn +a1n’xn+2 +xn+m= bm ’ (m) ’ 隣接端点(5) a11x1 + a12x2 + ‥‥ + a1nxn+xn+1 = b1 a21x1 + a22x2 + ‥‥ + a2nxn +xn+2 = b2 ‥‥ ‥‥ am1x1 + am2x2 + ‥‥ + amnxn +xn+m = bm (1) (2) (m) (2)/a21 x1 + a12/a21x2 + ‥‥ + a1n /a21xn+1 /a21xn+1 (1)-a11×(2)’ = b1 /a21 (2)’ 0+(a22-a11a12/a21)x2 + ‥ + (a2n-a11a1n /a21)xn-a11 /a21xn+1 +xn+2 = b2-a11b1 /a21 (1)’ (m)-am1×(1)’ 0+(am2-am1a12/a21)x2 + ‥ + (amn-am1a1n /a21)xn-am1 /a21xn+1 +xn+m = bm-am1b1 /a21 (m)’ a12’x2 + ‥‥ + a1n’xn + xn+1 + a1n’xn+2 x1 + a22’x2 + ‥‥+ a2n’xn ‥‥ am2’x2 + ‥‥+amn’xn = b1 ’ (1) ’ + a1n’xn+2 = b2 ’ (2) ’ +a1n’xn+2 +xn+m = bm ’ (m) ’ ‥‥ 隣接端点(6) a12’x2 + ‥‥ + a1n’xn + xn+1 + a1n’xn+2 x1 + a22’x2 + ‥‥+ a2n’xn ‥‥ am2’x2 + ‥‥+amn’xn = b1 ’ (1) ’ + a1n’xn+2 = b2 ’ (2) ’ +a1n’xn+2 +xn+m = bm ’ (m) ’ ‥‥ Z=c1 x1+ c2 x2+ + cn xn = c1(b2 ’- a22’x2 - ‥‥- a2n’xn - a1n’xn+2 ) + c2 x2+ = c1 b2 ’+(c2 - a22’ ) x2 ‥ +(c2 - a22’ ) xn - a1n’xn+2 + cn xn 例 Z=60x1+80x2 s.t. x1 + x2≦10 4x1+6x2≦48 0≦x1, 0≦x2 Z=60x1+80x2 s.t. x1 + x2 +x3 = 10 (1) 4x1+6x2 +x4 =48 (2) 0≦x1, 0≦x2 , 0≦x3 , 0≦x4 Non-Basic Variables 8 ③ (0,8,2,0) ① 00 (0, 0,10,48) Basic Variables ① x1 ,x2 x3 , x4 ③ x1 , x4 x2 , x3 (2’)=(2)/a22 2/3x1+x2 +1/6x4 =8 (2’) (1’)=(1) - (2’) 1/3x1 + x3 ー1/6x4 =2 (1’) 1/3x1 + x3 ー 1/6x4 = 2 (1’) 2/3x1 +x2 +1/6x4 = 8 (2’) Z=60x+80x2=60x1+80 (8-2/3x1-1/6x4) Z = 20/3 x1 – 40/3x4 + 640 Simplex Method Phase I n 次元 * ひとつの端点には, 個の隣接端点がある. どの端点を選ぶか? (どの変数が次の基底解になるか?) Z Z Z Z Z ( x ) ( , , , , ) x1 x 2 xi xn Max( Z Z Z Z , ,, , ) x1 x 2 xi xn Z Z Simplex Method Phase I (cont.) Z=60x1+80x2 Z Z , ) (60,80) x1 x 2 Max(60,80) 80 Z ( x ) ( x2 is selected as a new basic variable Z Z Z ( , ) x1 x 2 x2 ③ 8 (0,8,2,0) ①00 ④10 (0, 0,10,48) (10, 0, 0,8) Simplex Method Phase II m個の制約条件式 * m 個の基底変数. * m 個の基底変数の内,どの基底変数が非基底変数になるか? x1 + x2 +x3 = 10 4x1+6x2 +x4 =48 x3, x4 48 10 0 x3 x1 = x2 +x3 0 = 10 6x2 +x4 =48 x4 8 ② (0,10,0,-12) x2 ③ 8 (0,8,2,0) 10 x2 -12 0 ① 0 x4 is selected as a new non-basic variable (0, 0,10,48) ③ is selected as a corner point 10 シンプレックス法の解法手順 Step.1 初期実行可能解を求める. Step.2 目的関数を改善する隣接端点を調べる 無い場合:その点が最適解 ある場合:Step 3へ Step.3 目的関数を最も改善する方向を決定する. (どの変数が次の基底解になるかを決める) Step.4 制約条件を満たす中で,目的関数を最も改善する端点を決定する. (どの変数が次の非基底解になるかを決める) Step 2へ 解なし[実行可能領域無し] x1 + x2≧10 2x1+x2≦8 0≦x1 0≦x2 x2 10 8 4 10 x1 How to solve LP with Excel? Spread Sheet Example A company produces two products P1 and P2 with three materials M1, M2, and M3. 1kg of M1, 2kg of M2, and 3 kg of M3 are used to produce 1 kg of P1. Similarly, 7kg of M1, 4kg of M2, and 2 kg of M3 are used to produce 1 kg of P2. However, they have only 140kg of M1, 100kg of M2, and 120 kg of M3. Obtain the best combination of product P1 and P2, when the benefits of 1kg of P1 and that of P2 are 3US$ and 5US$ respectively? Z=3x1+5x2 s.t. x1 + 7x2≦140 Z=3x1+5x2 s.t. x1 + 7x2 +x3 =140 2x1 +4x2≦100 2x1 +4x2 3x1 +2x2≦120 3x1 +2x2 0≦x1, 0≦x2 +x4 =100 +x5 =120 0≦x1, 0≦x2 ,0≦x3, 0≦x4 , 0≦x5 Simplex Table(1) Z=3x1+5x2 x1 + 7x2 +x3 =140 s.t. 2x1 +4x2 +x4 =100 3x1 +2x2 +x5 =120 0≦x1, 0≦x2 ,0≦x3, 0≦x4 , 0≦x5 Z - 3x1 - 5x2 =0 Variable (1) I (2) (3) (4) B.V. Z Z 0 1 x3 140 0 x4 100 0 x5 120 0 x1 x2 x3 Marginal x4 x5 -3 -5 0 0 0 1 7 1 0 0 140/7 = 20 2 4 0 1 0 100/4 = 25 3 2 0 0 1 120/2=60 Simplex Table(2) Basic (1) I (2) (3) (4) (5) II (6) (7) (8) Variable Variable Z x1 x2 x3 Z x3 x4 x5 Z x2 x4 x5 0 1 -3 -5 140 0 1 100 0 120 Marginal x4 x5 0 0 0 7 1 0 0 140/7 = 20 2 4 0 1 0 100/4 = 25 0 3 2 0 0 1 120/2=60 100 1 -16/7 0 5/7 0 0 20 0 1/7 1 1/7 0 0 20/ (1/7) = 140 (2)÷7 20 0 10/7 0 -4/7 1 0 20/ (10/7) =14 (3)-(6)×4 80 0 19/7 0 -2/7 0 1 80/ (19/7)≒ 30 (4)-(6)×2 (1) - (6)×(-5) Simplex Table(3) Basic (5) II (6) (7) (8) (9) III (10) (11) (12) (13) IV (14) (15) (16) Variable x1 x2 x3 Marginal x4 x5 5/7 0 0 1 1/7 0 0 20/ (1/7) = 140 (2)÷7 10/7 0 -4/7 1 0 20/ (10/7) =14 (3)-(6)×4 0 19/7 0 -2/7 0 1 80/ (19/7)≒ 30 (4)-(6)×2 132 1 0 0 -1/5 8/5 0 18 0 0 1 1/5 -1/10 0 14 0 1 0 -2/5 7/10 0 42 0 0 0 4/5 -19/10 1 142.5 1 0 0 0 9/8 1/4 (9)-(16)×(-1/5) Variable Z Z x2 x4 x5 Z x2 x13 x5 Z x2 x1 x3 100 1 -16/7 0 20 0 1/7 20 0 80 (1) - (6)×(-5) (5) - (11)×(-16/7) 18/ (1/5) =90 (6) - (11)×1/7 (7) ÷10/7 42/ (4/5) = 52.5 (8)-(11)×19/7 7.5 0 0 1 0 3/8 -1/4 (10)-(16)×1/5 35 0 1 0 0 -1/4 1/2 (11) - (16)×(-2/5) 52.5 0 0 0 1 -19/8 5/4 (12)÷ 4/5 Shadow Price (Marginal Value) Z=3x1+5x2 s.t. x1 + 7x2 +x3 =140 2x1 +4x2 +x4 =100 3x1 +2x2 +x5 =120 0≦x1, 0≦x2 ,0≦x3, 0≦x4 , 0≦x5 (x*, x2*, x3 *, x4 *, x5 *)=(35,7.5, 52.5, 0, 0) Transport Problem Transport Problem Transport Problem (3 depots(i=1..3) & 4 customers(j=1..4)) Transportation Cost Cij j 1 2 3 1 2 1 1 xij [ton] Cij [B/ton] Si [ton] Cj [ton] 2 1 1 2 3 1 2 3 4 3 3 1 (S1 , S2 , S3 )=(100,200,150) (C1 , C2 , C3 , C4 )=(100,60,50,80) : Amount of Transported Cargo from i warehouse to j department : Transport Cost per ton from i warehouse to j department : Amount of Stock at i warehouse : Amount of Consumption at j department Transport Problem (3 depots(i=1..3) & 4 customers(j=1..4)) Total Cost ΣCij xij= 2x11 +x12 +x13 +3x14 +x21 +x22 +2x23 +3x24 +x31 +2x32 +3x33 +x34 x11 +x12 +x13 +x14≦S1 =100 x11 +x21 +x31 ≧C1 = 100 x12 +x22 +x32 ≧ C2 = 60 x13 +x23 +x33 ≧ C3 = 50 x14 +x24 +x34 ≧ C4 = 80 x21 +x22 +x23 +x24 ≦S2 = 200 x31 +x32 +x33 +x34≦S3 = 150 xij 0 30 70 50 10 0 50 0 0 0 0 80 Transport Problem Min. Σ Σ Cij・ xij s.t. Σ xij ≦ Si [ton] Σ xij ≦ Cj [ton] xij [ton] Cij [B/ton] Si [ton] Cj [ton] : Amount of Transported Cargo from i warehouse to j department : Transport Cost per ton from i warehouse to j department : Amount of Stock at i warehouse : Amount of Consumption at j department Dynamic Programming(1) DP is a mathematical technique used for the optimization of multistage decision process. In this technique, the decisions that affect the process are optimized in stage rather than simultaneously. This is done by dividing the original decision problem into small sub-problems that can be handled much more efficiently from a computational standpoint. DP is a systematic procedure for determining the combination of decisions that maximizes overall effectiveness or minimizes overall disutility. It is based on the principle of optimality enunciated by Bellman(1957). Bellman's Principle of Optimality: An optimal policy has the property that whatever the initial state and the initial decisions are, the remaining decisions must constitute an optimal policy with regard to the state resulting from the first decision. Dynamic Programming(2) Example: Shortest Path O D ○D.P. can be applied to problems that are ・ are non-linear. ・ have non-convex feasible region. ・ have discontinuous variables. ×D.P. is limited to dealing with problems with relatively few constraints DP complements LP Queuing Theory(1) Demand Arrival Average Arrival Rate Probability of k arrivals in t hours vs. Supply Service λ Average Arrival Rate μ Probability of k services ( t) k e t (t) k e λt k! in t hours k! Pn: Probability that there are n customers in the system Pn= (1- λ/μ)(λ/μ) n Lq: Average number of customers in the queue Lq= λ 2/(μ(μ- λ)) Wq: Average time a customer spends in the queue Wq= λ/(μ(μ- λ)) Pw: Probability that an arriving customer must for services Pw= λ /μ Queuing Theory(2) Demand Arrival Average Arrival Rate Probability of k arrivals in t hours vs. Supply Service λ Average Arrival Rate μ Probability of k services ( t) k e t (t) k e λt k! in t hours k! Pn: Probability that there are n customers in the system Pn= (1- λ/μ)(λ/μ) n Lq: Average number of customers in the queue Lq= λ 2/(μ(μ- λ)) Wq: Average time a customer spends in the queue Wq= λ/(μ(μ- λ)) Pw: Probability that an arriving customer must for services Pw= λ /μ Queuing Theory(3) Lq Lq 10 50 9 8 40 7 6 30 5 4 20 3 2 10 1 0 00.0 0.1 0.2 0.3 0.4 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.5 0.6 0.7 0.8 0.9 1.0 λ /μ λ /μ Convex Function (Strictly Convex Function) a. One variable 1. Z[x 1 (1 - )x 2 ] Z[x1 ] (1 - )Z[x 2 ] 2. Z(x1 ) dZ(x1 ) (x 3 - x 1 ) z(x 3 ) dx d 2 Z(x) 3. 0 dx b. Multi variables 1. Z[x1 (1 - )x 2 ] Z[ x1 ] (1 - )Z[ x 2 ] dZ( x1 ) 2. Z( x1 ) (x3 - x1 ) z( x3 ) dx 3. t xx 0 2Z 2 x 21 Z 2 Z (x) x x 2 1 Hessian Matrix 2 Z xM x1 2Z x1x2 2Z 2 x2 2Z x M x2 2Z x1xM 2 Z x1xM 2Z 2 xM Report 1. Make a transportation problem on the condition that each number of shippers and customers is more than 3. 2. Solve it with Excel. 3. Make “what-if ” analysis. By the dead line, 25th July. Assignment
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