▁liter als . ▁ ▁Inform al ▁explanation ▁ ▁In ▁first ▁order ▁logic , ▁resolution ▁cond enses ▁the ▁traditional ▁s yl log isms ▁of ▁logical ▁inference ▁down ▁to ▁a ▁single ▁rule . ▁ ▁To ▁understand ▁how ▁resolution ▁works , ▁consider ▁the ▁following ▁example ▁s yl log ism ▁of ▁term ▁logic : ▁▁ ▁All ▁Gree ks ▁are ▁Europe ans . ▁ ▁H omer ▁is ▁a ▁Greek . ▁ ▁Therefore , ▁H omer ▁is ▁a ▁European . ▁ ▁Or , ▁more ▁generally : ▁▁▁▁▁▁ ▁Therefore , ▁▁ ▁To ▁rec ast ▁the ▁reasoning ▁using ▁the ▁resolution ▁technique , ▁first ▁the ▁cla uses ▁must ▁be ▁converted ▁to ▁conj unct ive ▁normal ▁form ▁( CN F ). ▁In ▁this ▁form , ▁all ▁quant ification ▁becomes ▁implicit : ▁universal ▁quant ifiers ▁on ▁variables ▁( X , ▁Y , ▁...) ▁are ▁simply ▁omitted ▁as ▁understood , ▁while ▁exist entially - quant ified ▁variables ▁are ▁replaced ▁by ▁Sk ole m ▁functions . ▁▁▁▁▁▁ ▁Therefore , ▁▁ ▁So ▁the ▁question ▁is , ▁how ▁does ▁the ▁resolution ▁technique ▁derive ▁the ▁last ▁clause ▁from ▁the ▁first ▁two ? ▁The ▁rule ▁is ▁simple : ▁▁ ▁Find ▁two ▁cla uses ▁containing ▁the ▁same ▁predicate , ▁where ▁it ▁is ▁neg ated ▁in ▁one ▁clause ▁but ▁not ▁in ▁the ▁other . ▁ ▁Perform ▁a ▁un ification ▁on ▁the ▁two ▁pred ic ates . ▁( If ▁the ▁un ification ▁fails , ▁you ▁made ▁a ▁bad ▁choice ▁of ▁pred ic ates . ▁Go ▁back ▁to ▁the ▁previous ▁step ▁and ▁try ▁again .) ▁ ▁If ▁any ▁un bound ▁variables ▁which ▁were ▁bound