Method: CLEAR_SEL_COND
Method: GET_ITEM_OF_CONJUNCTION
Method: CONSTRUCTOR
Method: CHECK_SEL_CONDITION_EXISTS
Method: MAKE_SELNET_ITEMS
Method: DNF_TO_CONJUNCTIONS
Method: MAKE_CONJUNCTION
Method: PO_FIND_OR_INSERT_SINGLETON
Method: GET_DNF_OF_KNNUM
Method: SELECTION_CONDITION_TO_SELNET
Method: INITIALIZE
Method: MAKE_CONJUNCTION_MULTI