–1 votes –1 votes Which of the following is valid first order formula? Mathematical Logic propositional-logic bad-question + – Saikat Dutta asked Nov 21, 2017 Saikat Dutta 547 views answer comment Share Follow See all 4 Comments See all 4 4 Comments reply junaid ahmad commented Nov 21, 2017 reply Follow Share Is it D)all of the above ? 0 votes 0 votes Saikat Dutta commented Nov 21, 2017 reply Follow Share no. Given ans is B. A is definitely wrong, but why isn't C a right option? 0 votes 0 votes joshi_nitish commented Nov 21, 2017 reply Follow Share let P(x,y) means " x likes y" $\exists (y)\exists (x)(P(x,y))$ $\rightarrow$ $\exists (x)\exists (y)(P(x,y))$ $\exists (y)\exists (x)(P(x,y))$ means "someone is liked by someone" $\exists (x)\exists (y)(P(x,y))$ means "someone like someone". now you can easily see that first is implying second, actually both RHS and LHS are equivalent statements. 1 votes 1 votes Shubhanshu commented Nov 21, 2017 reply Follow Share @Saikat Dutta How A is wrong? 0 votes 0 votes Please log in or register to add a comment.
0 votes 0 votes a is not valid. b and c valid. raviyogi answered Nov 21, 2017 raviyogi comment Share Follow See 1 comment See all 1 1 comment reply Saikat Dutta commented Nov 21, 2017 reply Follow Share Where did you get this arrow diagram from? 0 votes 0 votes Please log in or register to add a comment.