Rule #6 is Not an If-Than
Started by
tmorrison10
· started 2019-03-20 03:29
· last activity 2020-01-07 15:24
· 1 reply
How can you write out rule #6 as a sufficient and necessary formula when there is no If-then statement.
I thought it was made pretty clear that unless it says if-then it cannot be a S->N formula.
-
shunhe
· 2020-01-07 15:24
Hi @tmorrison10,
Thanks for the question! In this case, the rule can be diagrammed as an "if-then" because it's logically equivalent to what we express in an "if-then." It might not be explicitly expressed as one, but there's a way to express it as one that keeps the original meaning. The rule reads that "exactly one of Larisa's aisles is an end aisle." One way of saying this is that Larisa is either in aisle one or aisle nine, but not both.
L1 v L9 & ~(L1 & L9)
But another way of saying this in plain English is that if Larisa is in aisle 1, she's not in aisle 9. Similarly, if she's in aisle 9, she's not in aisle 1. Also, if she is not in aisle 1, she's in aisle 9, and vice versa. So we can write that as
L1 < - > ~L9
Hope this helps!
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