Which of the following propositions is tautology?
A.  (p v q)→q 

B.  p v (q→p) 

C.  p v (p→q) 

D.  Both (b) & (c) 

Option: C Explanation : A tautology is a statement that is always true.
Click on Discuss to view users comments. jigyasa gupta said: (2:54am on Thursday 21st March 2013)
evn in option b every condition is a tautology...
sanket said: (2:22pm on Monday 15th April 2013)
why c is ans why not b
Nirmal said: (3:14am on Friday 7th June 2013)
Yes why not b?
Srushti said: (1:13am on Friday 12th July 2013)
without writing the truth table how to know whether it is tautology or no?
Nilesh said: (11:03am on Friday 5th June 2015)
[C] = P (P>q) = p ( ~p q )= p ~p q= ( p ~p ) q= True q= ( True q ) = True
Hina varshney said: (3:37pm on Tuesday 29th August 2017)
Option a is also tautology..
Jay said: (5:47am on Tuesday 19th September 2017)
D both(b and c)is tautology
stotaw takele said: (10:42am on Sunday 29th April 2018)
why not only b explain why include c
Arya said: (7:37am on Sunday 3rd June 2018)
B is answer

A.  A tautulogy 
B.  A contradiction 
C.  Logically equivalent to p ^ q 
D.  All of above 
Option: C Explanation : Click on Discuss to view users comments. ajinkya said: (1:03am on Tuesday 2nd July 2013)
B'coz if u solve that eq. geting ans is same as that of p^q
Amarnath said: (7:10pm on Wednesday 31st July 2013)
 p  q ~p (~pvq)p^(~pvq)p^q 0  0  1  1  0  0  0  1  1  1  0  0  1  0  0  0  0  0  1  1  0  1  1  1 So C is the right answer
Akshita gupta said: (3:31am on Saturday 6th May 2017)
Mah answer Contradiction(B) what is right answer B or C
Sagar said: (6:06am on Thursday 15th February 2018)
Ans is Tautologyin boolean algebra equivalent eq: p (p` q)= (p p`) q= 1 q= 1 (tautology).

A.  a v b → b ^ c 
B.  a ^ b → b v c 
C.  a v b → (b → c) 
D.  None of these 
Option: B Explanation : Click on Discuss to view users comments. 
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