Distinguishing string selection Problem Instance: Given a set B of n,(bad) strings of length L, a set G of n2(good)strings of length L, two thresholds db and < g Objective: Find a string s such that for each string bE B d(s,b)≤db Bad strings and for any string g∈G, d(s,g)>d Center string Good Strings 2021/1/292021/1/29 7 Distinguishing String Selection Problem Instance: Given a set B of n1 (bad) strings of length L, a set G of n2 (good) strings of length L, two thresholds db and dg ( db < dg ). Objective: Find a string s such that for each string b  B, d(s, b)  db and for any string g  G, d(s, g)  dg . Bad strings Center string Good Strings