Doubt in Q7 mock test

[Shrishti Hegde]

Dear Sir/Ma'am ,

Greetings!

Could you please help with how to get the answer for Q7 in the mock test.

In the solution, the condition is as follows: 

if ((A and B)==False and (A or B)==True){

return (True)

}

else{

         return (False)

}

The above condition will never get satisfied, because if both A and B are False it is obviously not possible that either of the two will be True and hence the code will always return the value as 'False".

It would be great if you could correct me if I'm wrong and provide me with an explanation for the answer        

[DHARMA TEJA GODUMALA]

And Condition

X-True and Y true= then only the whole condition will be executed otherwise it is not

If anyone of them is false then the statement won't get executed

Or Condition

X-False or Y False = Then only the whole condition won't get executed in remaining all cases it gets executed.

if ((A and B)==False and (A or B)==True){

return (True)

}

else{

         return (False)

Now in the above 

Case 1.   A  is True ,B is False the condition(if ((A and B)==False and (A or B)==True) )gets executed and return True.

Case 2.   A is False, B is True the condition(if ((A and B)==False and (A or B)==True) )gets executed and return True.

Any one of X.year == Y.year , X.Genre== Y.genre is true and other is false then the code should be executed.

[MANMAY SINGH]

Hey, Dharma I have a doubt.

In case 1:

we have A = True and B = False

So, in my opinion the statement "(A and B) == False" will be False as both the values A and B should be false to make it a True.

Therefore in this statement "if ((A and B)==False and (A or B)==True" we have two things which are separated by "and" which means that both the

condition should be true to execute the code.

i.e. first condition: (A and B)==False

second condition: (A or B)==True

So, to execute the code both the above condition should be true.

But what we saw that the first condition will return false and the second condition will true which makes it clear the the 'if' condition will not be executed.

Kindly clear my doubt.

[DHARMA TEJA GODUMALA]

Case 1 
we have A = True and B = False 

first condition: if((A and B)==False) then this will be true, it won't be false because (False==False is true)

second Condition if( (A or B)==True) then this will be true, it won,t be false because (True== True is true)

So both will be true 

Hope it helps you

[Shrishti Hegde]

Yes, Mr. Manmay, I agree with you. I had the same doubt. You explained it better than I did. Thank you very much!

[MANMAY SINGH]

See, Dharma. I totally agree with you on this (False==False is true).

But in the first condition "(A and B)==False" will only return True if both A = False and B = False.

But we are given that A = True and B = False.(you can see Case 1 in your explanation in reply to Shrishti.)

--

Manmay Singh_._._._._

[DHARMA TEJA GODUMALA]

if(False== False) condition is equal as If (True).

I hope now you will get it clearly.

[DHARMA TEJA GODUMALA]

((True and False)== False)  is a True Condition.

For And Condition to make it true both A should be True,B Should be True in remaining all case it is false.

[MANMAY SINGH]

Okay, now I have another doubt in your explanation. 

Here, the sign '==' is used for the equality.

And here it is being used as "A and B" that means we need to see both the value 'A' and 'B' equal to False.

I come up to this conclusion that if somewhere it is written "X.maths == 90" then we will look for the marks in maths for the card X exactly equal to 90.

And if it is written as "X.maths and X.physics == 90" then we will look for the marks in maths and physics both to be exactly equal to 90.

See I need the result on this with explanation:

1. A = False

    B = False 

then,  A and B == ?

2. A = True

    B = False

then,  A and B == ?

By the way thanks for taking part in the discussion and replying

[DHARMA TEJA GODUMALA]

Always the below mentioned conditions will be True.

And Condition

False and False= False

False and True= False

True and False= False

True and True = True

Or Condition

False or False= False

False and True= True

True and False= True

True and True= True

Hope it helps you

[DHARMA TEJA GODUMALA]

Sorry typing mistake in above the message

And Condition

False and False= False

False and True= False

True and False= False

True and True = True

 In Or condition

False or False= False

False or True= True

True or False= True

True or True= True

Hope it helps you

[MANMAY SINGH]

Totally agree with you.

But let me think for some time because what I want to ask is taking longer than expected in typing.

So, wait I am asking my doubt.

[MANMAY SINGH]

To be precise, we have two types of situation here:

1.   If (X and Y)

2.   (P and Q) ==

In the first situation we have to check whether both X and Y is true or not. If both are true then the code will execute and if both are false then the code will not get executed.

But in the second situation we are marking the values of P and Q to be exactly something.

 

The key difference between situation 1 and 2 is that in 1 we have ‘if’ and in 2 we have ‘==’.

And in ‘if’ we want conditions to be true but in ‘==’ we want conditions to be exact of some value.

 

So, regarding the question in Mock Test we have

In place of X:  “(A and B) == False”

In place of Y:  “(A or B) == True”

In place of P: A

In place of Q: B

Just tell me if I am right or wrong. If I am wrong what are those points.

[MANMAY SINGH]

Okay, this is what exactly I want to ask:

If it is given that “A = True and B = False” what is the difference between:

1.  If (A and B == False)

2.  A and B == False

3.  If (A and B)

[MANMAY SINGH]

Is there any difference between:

1. if (A and B == 90)

2. if (A == 90 and B == 90)

[MANMAY SINGH]

3. if ((A and B) == 90)

[DHARMA TEJA GODUMALA]

Case 1 

A= True ,B= False

X:  "(True and False)==False"  then X will be "True", because false==false
case 2 

A= True ,B= True

X: "(True and True)==False" then X will be false ,because True != False

Main Condition :   "if ((A and B)==False and (A or B)==True)"  

so put the case 1 in above Main condition

if((True and False)== False and (True or False)==True)

the above condition will now be reduced to if((false ==false and True ==True) and it further reduces to if (True and True) and it reduces further to if(True).

Now put case 2 in our main condition

if((True and True)==False and (True or True)==True)

the above condition will now be reduced to if((True==False and True== True) and it further reduces to if (False and True) and further reduces to if(False).

Hope it clears your doubt.

[DHARMA TEJA GODUMALA]

1. If (True and False==False) is further reduced to If( True and True) and it is further reduced to If (True) then you will enter into the loop.

2. True and False==Flase is reduced to True and True and it is further reduced to True.

3. If (True and False) is further reduced to IF(False) 

[Antony]

1. if (A and B == 90)

2. if (A == 90 and B == 90)

3. if ((A and B) == 90)

First of all, I think you are probably overthinking this. What you are trying to do in your various statements is mix boolean variables (A and B which holds only TRUE or FALSE) with a number.

Common behavior for most programming languages would be to treat a non zero integer to be "FALSE".  Again, this is subjective to the programming language.

So if A = TRUE, then  "A and  0"  might give you  FALSE,  "A and  1"  might give you  TRUE . But at the same time, if you try to do "A == 1" , that might give you FALSE.

I think your 1 and 2 might throw syntax error in most cases, because of missing parenthesis. 3 might return TRUE , if A and B are both TRUE.  

[Malabika Guha Mustafi]

Let X and Y be two rows in the “Library” table. We call books X and Y compatible if either published in the same year or the same genre but not both. Let CompatiblePair(X, Y) be a procedure to find whether X and Y are compatible. Choose the correct implementation of the procedure CompatiblePair.

I approach the problem in very simple way.

option 1) A or B true then return true(  but it may be true for both true since OR operation so it is discarded.)

option2) Again OR option between  Year and Genre( so it may be true for both true  so it is discarded)

option 3) same logic OR operation between ( (A and B)=false OR ( A OR B)=true,) still the option is open when A and B both true .

option 4) And operator so (A OR B= true and (A AND B )= false )implies A and B can not be both true.

Is it Ok?

[AC]

Hi,

I apologize for chiming in without reading the entire discussion thread:

I answered correctly for Q7 and this is how I interpreted the following psuedo-code block:

 

 

My interpretation:

1. (A and B) == False means : if the 2 conditions "A is TRUE" AND "B is True" - Both  conditions- turn out to be FALSE. This can happen iff either A is true OR B is true, but NOT while both A and B is TRUE (at the same time). 'Çause in that case (A and B) then would be == TRUE. Right?

2.  (A OR B) == True means : if either the condition "A is TRUE" OR the condition "B is True" - any one turns out to be TRUE.

3. So this checks out what is asked in the question (exclusive OR condition) - if either is true but not BOTH, type of a scenario.

Best.

[MANMAY SINGH]

Guys, just loved the way you all explained. Simply amazing. Now, this forum truly makes sense to clear doubts.

Absolutely amazing. 

Now, I will try to put my all efforts to clear the Qualifier so that I would be a part of this community.

Thanks guys.

[Srinath Sai]

Listing the four combinations below:

(1) X.Year == Y.Year and X.Genre == Y.Genre

(2) X.YEAR == Y.Year and X.Genre ≠≠ Y.Genre

(3)X.YEAR ≠≠ Y.Year and X.Genre == Y.Genre

(4)X.YEAR ≠≠ Y.Year and X.Genre  ≠≠  Y.Genre

Option 1 is wrong: A or B means combinations (1), (2), and (3). which is wrong as it includes (1) also, which means both, while the problem asks to consider only either or and not both.

,

Option 2 is wrong: As, here again, A or B means combinations (1),(2), and (3). which is wrong as it includes (1) which means both, while the problem asks to consider only either or and not both.

Option 3 is wrong: A and B False excluding Option (1) the rest of the combinations, i.e., (2),(3),(4); 

                                 A or B true means the combinations (1),(2),(3)

(A and B false) OR (A or B True) is an OR statement, and so, we take the Union of the above, 

i.e., {(2),(3),(4)} ∪ {(1),(2),(3)} which gives the result {(1),(2),(3),(4)} which is wrong, as going by the question (1) and (4) can't be considered.

Option 4:  A and B false means, (2)(3)(4); 

                              A or B true means (1),(2),(3)

(A and B false) AND (A or B True) is an AND statement, and so, we take the Intersection of the above.

i.e., {(2),(3),(4)}  ∩  {(1),(2),(3)}  which is (2), (3).

(2) and (3) are the two possibilities that have either the 'same year' or the 'same genre', and this matches with what is stated in the question.

So, Option 4 is correct.