I do some rock climbing, and the most common knot you see is the double-figure 8: That's because you can tie it at any point in the rope to create a loop for other climbers to latch into. It also gets tighter as you pull from any direction: the loop or either of the two single ropes coming out. However, I am often faced with a different problem: Say you have an infinitely long pole that you need to tie a rope around. You have to make a loop that will grip the pole tighter as the rope is pulled. You have access to one end of the rope, not both. You also need a knot that has this property of getting tighter as the rope is pulled. Is there any such knot that fits this description?