Tuesday, 3 July 2007

oc.optimization control - Optimization over permutation?

It may be the case that simulated annealing and genetic algorithms are relatively complicated to understand, bound and implement in this instance.



Instead, a very easy starting point would be a simple hill-climbing algorithm.



Start with an arbitrary (or better, random) initial permutation pipi.



The set of moves is the set MM of permutations that you can reach by transposing two elements of the permutation.



While there is a move that decreases ff,



  • Make the move to reach a new current permutation.


  • Compute the new set of moves (or rather, their profits f(pi)f(pi) for a move reaching pi).


This will get you to a local minimum at a cost of O(n2)cdotC(n), per move, where C(n) is the cost of calculating f(pi) for a permutation of [n].



Extremely simple and probably not too costly as a first step. You may be able to prove some sort of worst case bound between a local optimum and a global optimum.

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