The equivalent resistance between A and B is
0.5
1
2
4
There are two parallel combination of resistors
Rparallel = 1×11+1 = 12 for both of them.
Now, they are in series
So, R = 0.5 + 0.5 =1
The equivalent resistance between A and B is:
In the diagram, resistance between any two junctions is R. Equivalent resistance across terminals A and B is