Question 996678
<pre>
1. A&B 
2. AvC  
              :. (A->B) & (C->A)

Your prof is wrong.  This argument is not valid.

Here is the counter-example:

Suppose that A is false, B is true, and C is false.

Then A&B is false, AvC is false, therefore the
conjunction of the premises (A&B)&(AvC) is false.

Now let's look at the conclusion:

A->B is true, C->A is true, therefore (A->B) & (C->A) is true.

So this is a case where the conjunction of premises is false
and the conclusion is true.

So the argument is invalid.  Be sure to tell your prof why.

Edwin</pre>