process:

> Randomly pick a loop and also consider its mirror image under the symmetry; then add up the force contributions of both these loops.

In that way, we do not change the expectation value of the sum, but, due to the correlation, the variance is much smaller. In that way, it is possible to compute force contributions where a naive approach would require excessive effort due the huge variation, as in the system discussed in Section \[sec:cylinders\].

Parallelization
---------------

In the Worldline formalism the calculation of contributions to the total energy (or force) can be performed independently for each grid point. Also, for each grid point, the contribution of each loop to the energy (or force) does not depend on the contribution of the other loops. Thus the problem is easily seen as being embarrassingly parallel, and furthermore the basic component – processing a loop – does not require overy complex calculations (in the sense of memory requirements and algorithmic effort). As the worldline method is a probabilistic approach, the accuracy of the calculation can be increased (within reasonable limits dictated by computational effort) by increasing the number of grid points, number of loops, and the number of points 