With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Wyoming is a place.
text_B: In quantum mechanics , a sum rule is a formula for transitions between energy levels , in which the sum of the transition strengths is expressed in a simple form .. quantum mechanics. quantum mechanics. Sum rules are used to describe the properties of many physical systems , including solids , atoms , atomic nuclei , and nuclear constituents such as protons and neutrons .. The sum rules are derived from general principles , and are useful in situations where the behavior of individual energy levels is too complex to be described by a precise quantum-mechanical theory .. In general , sum rules are derived by using Heisenberg 's quantum-mechanical algebra to construct operator equalities , which are then applied to the particles or energy levels of a system .. Heisenberg. Werner Heisenberg
not_related.