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+25 votes

Which one of the following is the most appropriate logical formula to represent the statement?

 "Gold and silver ornaments are precious".
The following notations are used:        

  • $G(x): x$ is a gold ornament
  • $S(x): x$ is a silver ornament        
  • $P(x): x$ is precious
  1. $\forall x(P(x) \implies (G(x) \wedge S(x)))$
  2. $\forall x((G(x) \wedge S(x)) \implies P(x))$
  3. $\exists x((G(x) \wedge S(x)) \implies P(x))$
  4. $\forall x((G(x) \vee S(x)) \implies P(x))$
in Mathematical Logic by Boss (17.5k points)
edited by | 2k views
How can we know that an ornament cannot be made of gold and silver both. We see ornaments that have both gold in some parts and silver in other parts. We cannot judge the ornaments with this given information ryt? Moreover then what will be the meaning of this " gold or silver ornaments are precious"?

5 Answers

+42 votes
Best answer

The statement could be translated as,If $x$ is either Gold or Silver, then it would be precious. Rather than,

If $x$ is both Gold and Silver, as an item cannot both Gold and silver at the same time.

Hence Ans is (D).

by Active (4.2k points)
edited by
well , if we think about it an item can be both gold and silver at the same time BUT here in this context an item cant be gold and silver at same time because here gold & silver items are disjoint sets ... it's something we have to understand from the question
Yes "and" word is confusiing and leading to wrong answer. Ornament can not be both Gold and Silver at same time.
These logic are more confusing. Sometimes propositions doesn't convey any real meaning if we try to solve them according to simple english sentence then we might do it wrong.

But here we have to use intuition.. /
+4 votes

"Gold and silver ornaments are precious"

For all x, x can be either Gold or Silver ornament then the x is precious.

by Veteran (59.2k points)
+3 votes

Option D this is just Same as lion and tiger question 

by Boss (11.7k points)
+2 votes
This statement can be expressed as => For all X, x can be either gold or silver then the ornament X is precious => For all X, (G(X) v S(x)) => P(X).
by Loyal (9.9k points)
0 votes

Option D

First thing that we need to keep in mind is to decide the domain. Since, they did'nt specified what x is,  we will take x as all ornaments in the universe.

Second thing, Here in the question the word and is misleading & it does'nt mean that the ornament will be Gold & Silver. It can either be Gold or Silver.

Third is correct choice of quantifier.

if we use existential quantifier, it will mean that at least one Gold or Silver ornament is precious, which is not what the statement is saying. if the ornament is Gold or Silver then it will be precious.(all Gold or Silver ornament are precious). So we have to use universal quantifier.


by (429 points)

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