Let $A\:\leq_m\:B$ denotes that language $A$ is mapping reducible (also known as many-to-one reducible) to language $B$. Which one of the following is FALSE?
$A \leq_m B$ means $A$ cannot be harder than $B$. (Since $A$ can be reduced to $B$, instead of deciding $A$, we can now decide $B$)
So, the first 3 options are correct. Option (D) is false, as $B$ is not recursively enumerable doesn't guarantee $A$ is not recursively enumerable.
@ Arjun sir ,
can you explain a bit more detailed way pls
i didn't get why the first three options are correct
thanks in advance
@ravee_rocks I have a small problem.
That is if M is RE then L is RE .
But here L also can be Recursive.
please explain this
This slide explains everything
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