问答题(z)(P(x)∧(x)R(x,z)→(y)Q(x,y))∨R(x,y)
问答题(x)(y)(R(x,y)∧Q(z))
问答题(x)(P(x)∧(x)Q(x))∨((x)R(x,y)∧Q(z))
问答题(x)(P(x)∧R(x))→((x)P(x)∧Q(x))
问答题若自然数序列(d1,d2,…,dn)满足d1>d2>…>dn,则当它为一简单无向图的度序列时有