andtrueXXandfalseYfalseiftrueXYXiffalseXYYadd0XXaddsXYsaddXYfirst0XnilfirstsXconsYZconsYfirstXZfromXconsXfromsX2.1andtruex0andfalsex0iftruex0x1iffalsex0x1add0x0addsx0x1first0x0firstsx0consx1x2fromx0addsXYaddXYfirstsXconsYZfirstXZfromXfromsXtruefromXfromsXandtrueXXandfalseYfalseiftrueXYXiffalseXYYadd0XXaddsXYsaddXYfirst0XnilfirstsXconsYZconsYfirstXZfromXconsXfromsXfromXfromsXfromsz0fromssz0fromssz0fromsssz0fromssz0fromssz0fromsssz0fromsssz0z0sz0AProVEunknownStatistics for single proof: 100,00 % (8 real / 0 unknown / 0 assumptions / 8 total proof steps)http://aprove.informatik.rwth-aachen.deJohnDoe