With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: World War II involved guns.
text_B: The characteristic state function in statistical mechanics refers to a particular relationship between the partition function of an ensemble .. statistical mechanics. statistical mechanics. partition function. partition function ( statistical mechanics ). ensemble. Statistical ensemble ( mathematical physics ). In particular , if the partition function P satisfies. partition function. partition function ( statistical mechanics ). in which Q is a thermodynamic quantity , then Q is known as the `` characteristic state function '' of the ensemble corresponding to `` P '' .. ensemble. Statistical ensemble ( mathematical physics ). Beta refers to the thermodynamic beta .. thermodynamic beta. thermodynamic beta
not_related.