The following diagram shows that 52 \(\not \Rightarrow\) 21 is a code 6 non-implication, and the theory of transferability then shows that it is actually a code 4. It follows that the non-implication 309 \( \not \Rightarrow \) 21 is not just a code 6 non-implication, but is also a code 4 non-implication.

21 This form is negation transferable
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23
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27
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31
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32
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10
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80
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334 \( \not \Rightarrow \) 18
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67
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This form is transferable 52
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309

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