FOL question

horlicksgrabber · #1 $Old$ November 16th, 2008, 08:01 AM

Could somebody just tell me how to write :

James is wearing a grey scarf?

in first order logic?

Thanks in advance

clic-clac · #2 $Old$ November 16th, 2008, 09:28 AM

Wow that seems imprecise.. That depends on how you define your properties. For instance, that could be
1) if $P(x)$ means " $x$ is james" and $Q(x)$ means " $x$ wears a grey scarf", it would be:

$\forall x P(x) \Rightarrow Q(x)$

2) If $P(x)$ means " $x$ is james", $Q(x,y)$ means " $x$ wears $y$ ", $S(x)$ means " $x$ is a scarf" and $G(x)$ means " $x$ is grey", then it would be

$\forall x P(x) \Rightarrow \exists y ( S(y) \wedge G(y) \wedge Q(x,y) )$