Originally posted by: jef_ti

Hi all,

i was testing a minimization method and had this strange behavior, why solver tried to minimize a value when the 0 was already achieved?


// Tardiness of applied activities
dexpr int totalAtraso = sum(e in TodasAtividades) ((sizeOf(dvEscalonamentoAtividadesRota[e]) - e.transitTime) * presenceOf(dvEscalonamentoAtividadesRota[e]));

minimize totalAtraso;


Engine log:

!

---

! Minimization problem - 142 variables, 535 constraints
! Preprocessing : 88 extractables eliminated
! TimeLimit = 30
! Initial process time : 0,00s (0,00s extraction + 0,00s propagation)
! . Log search space : 1.331,3 (before), 1.330,7 (after)
! . Memory usage : 0,9 Mb (before), 1,3 Mb (after)
!

---

! Branches Non-fixed Branch decision Best
* 55 0,03s - 0
1.000 75 on _itv71 F 0
2.000 75 on _itv108 0
3.000 183 on _itv131 0
4.000 1 on _itv69 0
5.000 1 on _itv127 F 0
6.000 1 on _itv129 0
7.000 1 on _itv68 F 0
8.000 1 on _itv97 F 0
9.000 1 on _itv65 0
10.000 1 on _itv119 F 0
11.000 1 on _itv68 0
12.000 1 on _itv130 0
13.000 1 on _itv138 F 0
14.000 1 on _itv97 0
15.000 1 on _itv85 F 0
16.000 1 on _itv85 0
17.000 1 on _itv117 0
18.000 1 on _itv132 0
19.000 1 on _itv66 F 0
! Time = 6,65s, Average fail depth = 22, Memory usage = 3,4 Mb
! Branches Non-fixed Branch decision Best
20.000 1 on _itv71 0
21.000 1 on _itv42 0
22.000 1 on _itv138 F 0
23.000 1 on _itv119 F 0
24.000 1 on _itv116 0
25.000 1 on _itv34 0
26.000 1 on _itv88 0
27.000 1 on _itv121 F 0
28.000 1 on _itv138 0
29.000 1 on _itv134 0
30.000 1 on _itv42 0
31.000 1 on _itv30 F 0
32.000 1 on _itv127 0
33.000 1 on _itv128 F 0
34.000 1 on _itv102 0
35.000 1 on _itv63 F 0
36.000 1 on _itv139 0
37.000 1 on _itv42 0
38.000 1 on _itv86 0
39.000 1 on _itv26 F 0
! Time = 15,09s, Average fail depth = 21, Memory usage = 5,6 Mb
! Branches Non-fixed Branch decision Best
40.000 1 on _itv127 0
41.000 1 on _itv64 F 0
42.000 1 on _itv90 0
43.000 1 on _itv30 0
44.000 1 on _itv44 0
45.000 1 on _itv117 0
46.000 1 on _itv38 F 0
47.000 1 on _itv119 F 0
48.000 1 on _itv130 0
49.000 1 on _itv122 0
50.000 1 on _itv62 F 0
51.000 1 on _itv115 F 0
52.000 1 on _itv85 0
53.000 1 on _itv135 F 0
54.000 1 on _itv134 0
55.000 1 on _itv102 0
56.000 1 on _itv127 0
57.000 1 on _itv85 0
58.000 1 on _itv133 F 0
59.000 1 on _itv135 0
! Time = 21,92s, Average fail depth = 21, Memory usage = 7,4 Mb
! Branches Non-fixed Branch decision Best
60.000 1 on _itv86 0
61.000 1 on _itv53 0
62.000 1 on _itv46 0
63.000 1 on _itv50 0
64.000 1 on _itv115 0
65.000 1 on _itv64 0
66.000 1 on _itv129 0
67.000 1 on _itv51 0
68.000 1 on _itv102 0
69.000 1 on _itv120 F 0
70.000 1 on _itv63 F 0
71.000 1 on _itv131 0
72.000 1 on _itv99 0
73.000 1 on _itv113 F 0
74.000 91 on _itv67 0
75.000 1 on _itv24 F 0
76.000 1 on _itv88 0
77.000 1 on _itv60 F 0
78.000 1 on _itv68 F 0
79.000 1 on _itv115 0
! Time = 29,31s, Average fail depth = 21, Memory usage = 9,0 Mb
! Branches Non-fixed Branch decision Best
80.000 1 on _itv66 0
81.000 1 on _itv38 F 0
! Search terminated, replaying best solution found
!

---

! Solution status : Terminated by limit, solution found
! Number of branches : 81.337
! Number of fails : 36.312
! Total memory usage : 10,1 Mb (9,2 Mb CP Optimizer + 0,9 Mb Concert)
! Time spent in solve : 30,01s (30,01s engine + 0,00s extraction)
! Search speed (br. / s) : 2.709,9
!

---

Thanks in advance,

Jefferson Soares Biernastki
Coordenação de Sistemas Operacionais
Gerência de Tecnologia
ALL - América Latina Logística
Fone: (41) 2141-8613
Fax: (41) 2141-7408

Visit our website: www.all-logistica.com
#CPOptimizer
#DecisionOptimization

Originally posted by: SystemAdmin

Hello,
It could be because this part of the expression can be negative: sizeOf(dvEscalonamentoAtividadesRota[e]) - e.transitTime. This will happen, among other things if the interval variable is absent as, in this case, the value of sizeOf(dvEscalonamentoAtividadesRota[e]) will be 0. You could tell this expression to be always non-negative by saying that the value of sizeOf(dvEscalonamentoAtividadesRota[e]) when the interval is absent is e.transitTime. And in that case, you do not even need to multiply by presenceOf(dvEscalonamentoAtividadesRota[e]). That is :

dexpr 

int totalAtraso = sum(e in TodasAtividades) ((sizeOf(dvEscalonamentoAtividadesRota[e], e.transitTime) - e.transitTime);

Philippe
#CPOptimizer
#DecisionOptimization

Originally posted by: jef_ti

Wonderful tip, it worked perfectly.

Thanks.

!

---

! Minimization problem - 142 variables, 535 constraints
! Preprocessing : 88 extractables eliminated
! OptimalityTolerance = 0
! Initial process time : 0,00s (0,00s extraction + 0,00s propagation)
! . Log search space : 1.331,3 (before), 1.330,7 (after)
! . Memory usage : 0,9 Mb (before), 1,3 Mb (after)
!

---

! Branches Non-fixed Branch decision Best
* 55 0,02s - 0
! Search terminated, replaying optimal solution
!

---

! Solution status : Terminated normally, optimal found (tol. = 0)
! Number of branches : 56
! Number of fails : 4
! Total memory usage : 2,5 Mb (1,6 Mb CP Optimizer + 1,0 Mb Concert)
! Time spent in solve : 0,02s (0,02s engine + 0,00s extraction)
! Search speed (br. / s) : 3.589,7
!

---

Jefferson Soares Biernastki
Coordenação de Sistemas Operacionais
Gerência de Tecnologia
ALL - América Latina Logística
Fone: (41) 2141-8613
Fax: (41) 2141-7408

Visit our website: www.all-logistica.com
#CPOptimizer
#DecisionOptimization