Combinatorics 2017 Fall weekl note Teaching by:Professor Xiande Zhang Reference: Extremal Combinatorics with applications in Computer Science. 2nd Edition.Stasys Jukna,Springer. 2017.9.12 Notation: &6onc艾aten的 (2)for integer n>0 [n]:={1,2.....n} (3)A vector(or string)of length n over X （x1.“,rn.x:∈X,1∈n (4)i.e.that is. 3exist. →imply. s.t.such that ！unique, Combinatorics 2017 Fall week1 note Teaching by: Professor Xiande Zhang Reference: Extremal Combinatorics with applications in Computer Science. 2nd Edition.Stasys Jukna,Springer. 2017.9.12 Notation: (1) A set X (a collection of distinct elements) |X| :=# elements of X (2) for integer n > 0 [n] := {1, 2, · · · , n} (3) A vector(or string) of length n over X (x1, ·, xn).xi ∈ X, i ∈ [n] (4) i.e. that is. ∃ exist. ⇒ imply. s.t. such that. ! unique. 1