Fairness k=-1; (newvar i:=0 in while k =-1 do if f(i)>0 then k :=ielsei:=i+2 ll newvar i:=1 in while k=-1 do if f(i)0 then k:=ielse i:=i+2) Suppose f(i)<0 for all even number i.Then there's an infinite execution in the form of: ..→(clc',1)→(c2lc,o2)→..→(cnlc,on)→. An execution of concurrent processes is unfair if it does not terminate but,after some finite number of steps,there is an unterminated process that never makes a transition. Xinyu Feng Shared-Variable Concurrency Fairness k := −1; (newvar i := 0 in while k = −1 do if f(i) ≥ 0 then k := i else i := i + 2 k newvar i := 1 in while k = −1 do if f(i) ≥ 0 then k := i else i := i + 2) Suppose f(i) < 0 for all even number i. Then there’s an infinite execution in the form of: . . . −→ (c1 k c 0 , σ1) −→ (c2 k c 0 , σ2) −→ . . . −→ (cn k c 0 , σn) −→ . . . An execution of concurrent processes is unfair if it does not terminate but, after some finite number of steps, there is an unterminated process that never makes a transition. Xinyu Feng Shared-Variable Concurrency