Abstract: There is provided a method comprising: receiving a graph comprising nodes with directional edges each associated with a variable weight representing an interaction strength of the respective direction edge adjustable according to a respective range; calculating a current global value defined by a function of the variable weights of the directional edges; calculating a mismatch between the current global value and a desired global value, wherein multiple different combinations of assigned variable weights of the directional edges are associated with the desired global value within the tolerance requirement; determining when the mismatch is within a tolerance requirement representing desired global values; and one of: randomly adjusting the variable weights of the directional edges within the respective range, and iterating the calculating the mismatch and determining when the mismatch is not within the tolerance requirement, and outputting determined values for the variable weights when the mismatch is within