求解布尔表达式的完全积和表达式 Full sum-of-products form: 每个基本积项都包含了表达式中的所有变元 Algorithm 15.2:The input is a Boolean sum-of-products expression E=E(x1,x2,...,x).The output is a complete sum-of-products expression equivalent to E. Step 1.Find a product P in E which does not involve the variable x,and then multiply P by xi+x,deleting any repeated products.(This is possible sincexi+x=1,and P+P=P.) Step 2.Repeat Step 1 until every product P in E is a minterm,i.e.,every product P involves all the variables.求解布尔表达式E的完全积和表达式 Full sum-of-products form: 每个基本积项都包含了表达式中的所有变元