Complexity of Online Algorithms - CSIS

Paging Algorithm – Competitive Analysis
Online Paging Competitiveness Theorem:
• For any deterministic online algorithm A for paging, C A >= k
Question:
• Can the negative result in OPC Theorem be overcome
using randomization?
Proof Technique:
• One can view the offline algorithm as an adversary who is
not only managing a cache but is also choosing the inputs
• and in this case an adversary who also knows the state of
the algorithm (being analyzed).
• In case of a randomized algorithm, if the adversary knows
the state (in this case, current set of pages in the cache)
• then the adversary knows the random choices made by
the algorithm (in this case, the pages to be evicted)