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+3 votes
The CORRECT formula for the sentence, "not all Rainy days are Cold" is

(A) $\forall d (\text{Rainy}(d) \wedge \text{~Cold}(d))$

(B) $\forall d ( \text{~Rainy}(d) \to \text{Cold}(d))$

(C) $\exists d(\text{~Rainy}(d) \to \text{Cold}(d))$

(D) $\exists d(\text{Rainy}(d) \wedge \text{~Cold}(d))$
asked in Mathematical Logic by Veteran (73.2k points)  
edited by | 458 views
Is there typo in last option ? please correct it !

4 Answers

+7 votes
Best answer

Not all rainy days are cold.

In other words it says "Some rainy days are cold" or "Some rainy days are not cold"

Given statement is

<=> ∃ d[R(d) ^ ~C(d)]


answered by Loyal (3.2k points)  
selected by
+13 votes
A) No rainy days are cold

B) All non-rainy days are cold

C)Some non-rainy days are cold.

D) Some rainy days are not cold.

option D
answered by Loyal (2.7k points)  
Is option (A) statement correct?
Statement A  shoud be "all days are rainy days and they are not cold "
+1 vote

not all rainy days are cold : meaning "there are some rainy days which are cold" = "some days are rainy and not cold".

∃d{R(d) \scriptstyle \wedge ¬C(d)}


ans = option D

answered by Veteran (26.8k points)  
0 votes

(A)∀d(R(d)⋀~C(d)) = d(~(~R(d) V C(d))) (taking negation common)

                                   =∀d(~(R(d)->C(d)))= All days are not Rainy days and also are not Cold

(B)d(~R(d)->C(d))=The day which are not Rainy day are Cold

(C)∃d(~R(d)->C(d))=∃d(R(d)VC(d))=Some day are Rainy days or some days are Cold

(D)∃d(R(d)⋀~C(d))= Some Rainy days are not Cold

                                = ~ (∀d(R(d)->C(d))) (taking negation common)

                                =not all Rainy days are Cold

answered by Veteran (49.4k points)  
edited by
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