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PDS #8
| Question | Answer |
|---|---|
| What does Linking Constrain mean | in FLP facility can be used to serve costumers only if it has been opened |
| What are 3 reasons to prone a node | 1, Infeasibility = any feasible solution cannot be achieved anymore 2,Integrality = the delivers a feasible solution by LP-Relaxation 3,Bound = Node can no longer imrpove current best solution |
| What is Dynamic Programming (3) | 1, decomposition a problem into stage-by-stage sequence 2, with problem with complexity of at least n>=2 3,delivers optimal solutions |
| What is idea of Multi-Stage Decision-Making (2) | 1, decisions are dependent on the previous ones 2, i stage influence i+1 stage and so on |
| What is General Objective Function of Multi-Stage Decision-Making | G1(s1) = min ∑ gi(si,xi) gi (si,xi) ... cost or profit created at stage i G1(s1) .. optimal solution / optimal value of stage 1 |
| What are the constrains of General Multi-Stage Decision-Making Model (4) | 1, s i+1 = fi(si,xi) >> Next stage is determined by current one 2,s i+1 ∈ S i+1 >>> Next stage is a valid state 3,xi ∈ Xi(si) >>> xi is a feasible domain 4, si given >>> first stage is given |
| What are Decision Variables in Binary Knapsack Problem in Dynamic Programming (2) | 1, xi∈Xi(si) 2,Xi(si)= { {0,1} if wi<=si {0} of wi>si } ..feasable domain at stage i |
| What is s1 in Binary Knapsack Problem in Dynamic Programming | s1=C .. initial capacity si = remaining capacity at stage i |
| What are 3 constrains in Binary Knapsack Problem in Dynamic Programming | 1, s i+1 = si - wi*x1 2,S i+1 ∈ {0,1,...N} hypotetically possible capacity 3,s1=C is given |
| When is a dynamic programming solution feasible | when ALL THE CONSTRAINS in ALL THE STAGES are respected |
| What are further notation in dynamic programming to make it easier to overview | 1, sequence of decision (x1,x2,...xn) 2, sequence of states (s1,s2,..sn) |
| What are 3 important remark to Multiple-Stage Decision-Making Graphinc | 1, arcs should go all possible ways from sn=C up to si-xi*wi= 0 2, above each arcs there should be profit for only current decision 3,S1 should be written separatly |
| What is Bellman´s Optimality Principle | if the whole paths is optimal, then every remaining part also must bo optimal from state it started |
| What is Forward and Backward Recursion | Forward Recursion = calculate optimal solution / path Backward Recursion = recover other optimals paths if there were ties |