Question #167

[lcleme02]

"G will be assigned unless K is assigned."

Whenever I try and think about the answer in my head, I come up with G --> ~K but the correct response is ~G --> K. Can you walk me through the correct thought process? I would really appreciate it!

[celphi02]

The question in which I'm responding to:

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"G will be assigned unless K is assigned."

Whenever I try and think about the answer in my head, I come up with G --> ~K but the correct response is ~G --> K. Can you walk me through the correct thought process? I would really appreciate it!
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There's a very easy way to solve 'unless' statements.

Step 1. Change 'unless' to 'If not'
Step 2. Look for contra-positive

Question: "G will be assigned unless K is assigned."

Step 1 translation: G will be assigned IF NOT K is assigned.
~K --> G

Step 2: If A --> B contra-positive is If ~B --> ~A
~K --> G and the contra-positive is ~G --> K.

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If the contra-positive part is confusing you then do the following.

Example:
~A --> B

what you would do is negate both sides
~(~A) --> ~(B)

then switch both sides
~B --> A
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So in the example you gave:
~K --> G

negate both sides:
~(~K) --> ~(G)

then switch both sides:
~G -- > K

Hope this helps!!!

Email me anytime: Celphi02@gmail.com