Progressive Method Extend smallest cells 0123456 s r j it o:(0,0)(1,1) 0012 E1:(1,0)(0,1)2,1 1s1012 (12)(22132)(432e21山2 (5,4)(6,5) 3r2112 4 a 212 E2:(2,0)(3,1)(4,2)5j 212 63)(64)(1.32,3)6i[212 (3,3)(44)(55)(6,6) 2/2/2021 Topk Search(@ ICD E2013Progressive Method 2/2/2021 TopkSearch @ ICDE2013 20/42 Extend Smallest Cells E0 : (0, 0) (1,1) E1 : (1,0) (0,1)(2,1) (1,2) (2,2) (3,2) (4,3) (5,4) (6,5) E2 : (2,0) (3,1) (4,2) (5,3) (6,4) (1,3)(2,3) (3,3) (4,4) (5,5) (6,6)