Re: Setup and Rule Diagrams

[dimi.wassef@yahoo.com]

In the set-up of this game, Powerscore Answer Key comes to the following Inferences:

Via the contrapositive, if an organism does not respond to G, then it cannot respond to F.
Consequently, if an organism does not respond to G, it must respond to H. If an organism does not
respond to H, then it must respond to G (either it responds to G alone, or if it responds to F, then it
also responds to G under the fifth rule).

From this, I am very confused as to how the inference 'if an organism does not respond to G, it must respond to H...' was founded?

Thank you,

Dimi

[Adam Tyson]

It's because of the relationship of the F/G rule to the first rule of the game, Dimi, which states that "Each of the organisms responds to at least one of the antibiotics." If an organism does not respond to G then it cannot respond to F, but it must respond to one of the three antibiotics, so it must respond to H, the only one that's left.

[concrottrox11@gmail.com]

How do we get from the deduction that not G-->not F to not G-->H?

[Robert Carroll]

concrottrox11,

If G is out, F is out. So if G is out, the only antibiotic that works (and we need at least one, per the first rule) is H. So if not G, then H.

Robert Carroll

[mollylynch]

Can someone explain why if it does not respond to H, it must respond to G?

[Adam Tyson]

If an organism does not respond to H, it must respond to at least one of the other two antibiotics. It can either respond to F and G (because it cannot respond to F alone, since responding to F requires also responding to G) or it can respond to G alone. Either way, it must respond to G.

To help, here are all the possible combinations of antibiotics that a given organism might respond to:

G
H
GH
FG

There can never be an FH combination, nor can there be an F by itself, because of the rule that says if F, then G.