Question 385397
No because for a correspondence to be a function there must be a one-to-one correspondence. 
For each x value, there must be a unique y value. 
For cars, this means that each owner can only register one car in his or her name. 
As you know, some people have only one car but many people have multiple cars in their name. 
So there is not a one-to-one correspondence, so it can't be a function.
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However, the other way around it would work because each registration number (VIN number) can only have one owner. So R(M) is a function but M(R) is not.