Shaqra University
Collage of Science and Humanities Studies
Computer Sciences Department
1st semester 1435/1436
IA CS401
Assignment # 2
Model Answer
Q1: Create new facts from the existing facts (conclusion):
I)
a. Everything made of copper conducts electricity.
b. This wire is made of copper.
Premise1: Everything made of copper conducts electricity.
Premise2: This wire is made of copper.
Conclusion: Therefore, wire conducts electricity.
Q2: Write above sentences in Q1 as predicates with arguments.
P1: ∀x copper(x) à conducts_electricity(x)
P2: copper(wire)
C: copper(wire) à conducts_electricity(wire)
Q3: Determine whether or not above arguments are valid or not by
using a truth table for the premises and the conclusion.
argument: A —> B , A |- (A —> B)
A
T
T
F
F
B
T
F
T
F
A —> B
T
F
T
T
no counter example , so this argument is valid .
Q4: Translate the following English sentences to predicate logic
formulas. Choose your own constants, variables and predicate letters,
providing the key.
1) Giraffe is an animal who is tall and has long legs
animal(Giraffe) ∧ tall(Giraffe) ∧ long_legs(Giraffe)
2) Somebody in the physical class is smarter than everybody in the math class.
∃x physical_class(x) ,∀y math_class(y)→ smarter(x,y)
3) If anyone studied in the collage, then either graduates from it or not.
S(x): x studied in a collage / G(x): x graduated from collage
∀x[S(x) → [G(x) ∨ ¬G (x)]
4) All birds are animal and can fly.
∀X [bird(X) ∩ can_fly(X)]