▁database ▁of ▁D ▁sequences ▁is ▁given ▁by ▁▁ ▁Furthermore , ▁when ▁, ▁E ▁could ▁be ▁approxim ated ▁by ▁the ▁Po isson ▁distribution ▁as ▁▁▁ ▁This ▁expectation ▁or ▁expect ▁value ▁" E " ▁( o ften ▁called ▁an ▁E ▁score ▁or ▁E - value ▁or ▁e - value ) ▁assess ing ▁the ▁significance ▁of ▁the ▁H SP ▁score ▁for ▁un - g apped ▁local ▁alignment ▁is ▁reported ▁in ▁the ▁B LA ST ▁results . ▁The ▁calculation ▁shown ▁here ▁is ▁modified ▁if ▁individual ▁H SP s ▁are ▁combined , ▁such ▁as ▁when ▁producing ▁g apped ▁align ments ▁( des cribed ▁below ), ▁due ▁to ▁the ▁variation ▁of ▁the ▁statistical ▁parameters . ▁ ▁Make ▁two ▁or ▁more ▁H SP ▁regions ▁into ▁a ▁longer ▁alignment . ▁ ▁Sometimes , ▁we ▁find ▁two ▁or ▁more ▁H SP ▁regions ▁in ▁one ▁database ▁sequence ▁that ▁can ▁be ▁made ▁into ▁a ▁longer ▁alignment . ▁This ▁provides ▁additional ▁evidence ▁of ▁the ▁relation ▁between ▁the ▁query ▁and ▁database ▁sequence . ▁There ▁are ▁two ▁methods , ▁the ▁Po isson ▁method ▁and ▁the ▁sum - of - sc ores ▁method , ▁to ▁compare ▁the ▁significance ▁of ▁the ▁newly ▁combined ▁H SP ▁regions . ▁Suppose ▁that ▁there ▁are ▁two ▁combined ▁H SP ▁regions ▁with ▁the ▁pairs ▁of ▁scores ▁( 6 5 , ▁ 4 0 ) ▁and ▁( 5 2 , ▁ 4 5 ), ▁respectively . ▁The ▁Po isson ▁method ▁gives ▁more ▁significance ▁to ▁the ▁set ▁with ▁the ▁maximal ▁lower ▁score ▁( 4 5 > 4 0 ). ▁However , ▁the ▁sum - of -