Lower Bounds for Online Algorithms
نویسندگان
چکیده
What is an oline problem Unlike the offline problems that we get the whole input at the beginning, in an online problem we just have some part of the input in advance. The rest of the input are queries that arrive one by one. Upon the arrival of each request, we need to process as it is received. In analyzing online algorithms, we usually, do not really care about the ruing time. The source of hardness here is lack of information, not complexity assumptions like P 6= NP . Since the algorithm does not know the rest of the input it may not be able to make the optimum decisions. In online problems, we want to have a ”good solution”. How to measure a ”solution”? We compare the outcome of an online algorithm with the best possible offline solution. This is the notion of ”competitive ratio”, which is defined below:
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