The given relation R in set A={1,2,3,4,5,6} is defined as R={( a,b ):b=a+1}.
Thus, R={ ( 1,2 ),( 2,3 ),( 3,4 ),( 4,5 ),( 5,6 ) }.
Since, ( 1,1 ),( 2,2 ),( 3,3 ).....( 6,6 )∉R, hence R is not reflexive.
Since, ( 1,2 )∈R but ( 2,1 )∉R. Hence, Ris not symmetric.
Since, ( 1,2 ),( 2,3 )∈R but ( 1,3 )∉R, hence Ris not transitive.
Therefore, the given relation R={( a,b ):b=a+1} in the set A={1,2,3,4,5,6} is not reflexive, symmetric, or transitive.