Why it matters
Real systems face online decisions. Understanding shapes real-world algorithm design.
Advertisement
The architecture
Input arrives one at a time.
Decide + commit before next arrives.
Competitive ratio: online cost / offline optimum.
Advertisement
How it works end to end
Ski rental: rent or buy. Classic 2-competitive.
Paging: LRU is O(k)-competitive.
k-server: move server to satisfy requests.
Applications: caching, scheduling, ad allocation.