graphs

p1 is holding instance of r1..
p1 may request instance of r2
p2 is holding the instance of r2
p2 is requesting instance of r1
there no dead lock becuse there is no cycle..

p2 is requesting instace of r1

p1 is holding the instance of r1

both p1 and p2 may request instance of r2

but there is no deadlock because there is no cycle

P2 and P3 has the instance of R1

P1 and P4 has the instance of R2

P1 and P3 has no interuption on cycle..

there for no deadlock

P1 and P2 is holding a instance of R2 then P1 request instance of R1 but P2 is holding the instance of R1 then P2 request isntance of R3 but P3 is holding the instance of R3 then P3 request instance of R2 but P1 and P2 has the instance of R2..
R4 is undistured

there is deadlock

P1 and P2 is holding a instance of R2 then P1 request instance of R1 but P2 is holding the instance of R1 then P2 request isntance of R3 but P3 is holding the instance of R3..

R4 is undistured

there is deadlock