Question

give an example to a relation summetric but niether reflexive nor transitive

Answer 1

R={x:y and y= 2x (x,y)€ R}

let's take (1,2)€ R and (2,1)€ R
is symmetrical
but..
here (1,2) €R is not reflexes
for it should be (1,1)
as( 1,2) € R and (2,1) €R but (1,1) is not € R