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P: Raju Attends Class
Q: Rani Attends Class

$P \rightarrow Q$  : If Raju Attends the Class, then Rani will attend class.

For Modus Tollens implication we will consider
($P \rightarrow Q$) $\Lambda$(~Q) $\Leftrightarrow$ ~P

But why can't we consider

($P \rightarrow Q$) $\Lambda$(~P) $\Leftrightarrow$ <what could be conclusion here>
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P→Q  : If Raju Attends the Class, then Rani will attend class.

lets first explain this statement more

P Q P→Q
T T T
T F F
F T/F T



If Raju Attends the Class, then Rani will attend class means if Raju attends then Rani definitely attends but if Raju dosnt attend then Rani may or may not attend.

now explain given compound propositions

(P→Q) Λ(~Q) ⇔ ~P

"If Raju Attends the Class, then Rani will attend class" AND "Rani doesnt attend class"

if Rani doesnt attend then surely Raju doest becoz Rani attend only if Raju attend

as we know (P→Q) ⇔( ~Q→~P)            [contrapositive of (P→Q) ]

so above proposition ans is Raju doesnt attend (~Q)

 

(P→Q) Λ(~P) ⇔ <what could be conclusion here>

"If Raju Attends the Class, then Rani will attend class" AND "Raju doesnt attend class"

if Raju doesnt attend then Rani may or may attend (see from the table)

if Raju attend then Rani definitely attend

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