Question

Which one of the first order predicate calculus statements given below correctly expresses the following English statement?
Tigers and lions attack if they are hungry or threatened.

• A. $\forall x$[(tiger (x) $\wedge$ lion (x)) $\to${(hungry(x) $\vee$ threatened (x)) $\to$ attacks(x)}]
  
  
• B. $\forall x$[(tiger (x) $\vee$ lion (x)) $\to${(hungry(x) $\vee$ threatened (x)) $\wedge$ attacks(x)}]
• C. $\forall x$[(tiger (x) $\vee$ lion (x)) $\to${(attacks(x) $\to$ (hungry(x) $\vee$ threatened (x)) }]
  
• D. $\forall x$[(tiger (x) $\vee$ lion (x)) $\to${(hungry(x) $\vee$ threatened (x)) $\to$ attacks(x)}]
  
  

Answer 1

The correct option is D $\forall x$[(tiger (x) $\vee$ lion (x)) $\to${(hungry(x) $\vee$ threatened (x)) $\to$ attacks(x)}]



The given statement should be read as "If an animal is a tiger or a lion, then(if the animal is hungry or threatened, then it will attack). Therefore the correct translation is $\forall x$[(tiger (x) $\vee$ lion (x)) $\to${(hungry(x) $\vee$ threatened (x)) $\to$ attacks(x)}]
which is choice (d).