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: (11:54pm on Wednesday 20th March 2013)
evn in option b every condition is a tautology...
sanket said: (11:22am on Monday 15th April 2013)
why c is ans why not b
Nirmal said: (12:14am on Friday 7th June 2013)
Yes why not b?
Srushti said: (10:13pm on Thursday 11th July 2013)
without writing the truth table how to know whether it is tautology or no?
Nilesh said: (8:03am 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: (12:37pm on Tuesday 29th August 2017)
Option a is also tautology..
Jay said: (2:47am on Tuesday 19th September 2017)
D both(b and c)is tautology
stotaw takele said: (7:42am on Sunday 29th April 2018)
why not only b explain why include c
Arya said: (4:37am 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: (10:03pm on Monday 1st July 2013)
B'coz if u solve that eq. geting ans is same as that of p^q
Amarnath said: (4:10pm 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: (12:31am on Saturday 6th May 2017)
Mah answer Contradiction(B) what is right answer B or C
Sagar said: (4:06am 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. 
Syllabus covered in this section is
This Section covers Mathematical Logic Questions Answers
Who can benefit
Various Search Terms Used For This Section Are