判定问题的形式化表达 Definition 2.3.2.1.A decision problem is a triple (L,U,>where is an alphabet and L U C *An algorithm A solves (decides)the decision problem (L,U,>if,for every x EU, ()A(x)=1fx∈L,amd Pay attention to ()A(x)=0讨x∈U-L(c年L). the word "decide" 问题5：如果x不在U中，怎么解释？ For many decision problems (L,U,D)we assume U=D*.In that case we shall use the short notation(L,∑)instead of(L,∑*，)判定问题的形式化表达 Pay attention to the word “decide” 问题5：如果x不在U中，怎么解释？