Progressive Method Extending cells 0123456 s r a i t o:(0,0)(1,1) 00 1:(1,0)(0,1)(2, 18101 (1,2)(2,2) 2 e 3r 4 56 2/2/2021 Topk Search(@ ICD E2013Progressive Method 2/2/2021 TopkSearch @ ICDE2013 17/42 Extending Cells E0 : (0, 0) (1,1) E1 : (1,0) (0,1)(2,1) (1,2) (2,2)