Question
Let denote the statements “It is raining”, “It is cold”, and “It is pleasant”, respectively. Then the statement “It is not raining and it is pleasant, and it is not pleasant only if it is raining and it is cold” is represented by
Official answer and solution
- Official answer
- A
- From
- Official GATE 2017 answer key
Solution
Translate each component of the English compound sentence into propositional logic connectives.
Identify the propositional variables:
- : “It is raining”
- : “It is cold”
- : “It is pleasant”
Deconstruct the sentence into its two main conjunctive parts:
- “It is not raining and it is pleasant”: .
- “and”: represented by the logical conjunction .
- “it is not pleasant only if it is raining and it is cold”:
In propositional logic, the conditional construction “ only if ” translates to .
Here, is “it is not pleasant” (), and is “it is raining and it is cold” ().
Therefore, “ only if ” translates directly to .
Combining the two clauses with conjunction yields:
This corresponds to option A.
A
Confusing “A only if B” () with “A if B” ().
The answer is the one in the official GATE answer key. The solution is this site's own explanation.
Source
- Paper
- GATE 2017 Computer Science and Information Technology (CS) Session 2
- Question
- 11 of 65, printed as CS Q.11
- Section
- Computer Science and Information Technology
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