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Yuval Filmus
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Your proof system is neither sound nor completeconsistent, since $A$ is not a true proposition unless $A \equiv \top$, In which case $\lnot A \equiv \bot$ is not a true proposition. This argument shows that every sound proof system is also consistent.

Your proof system is neither sound nor complete, since $A$ is not a true proposition unless $A \equiv \top$, In which case $\lnot A \equiv \bot$ is not a true proposition. This argument shows that every sound proof system is also consistent.

Your proof system is neither sound nor consistent, since $A$ is not a true proposition unless $A \equiv \top$, In which case $\lnot A \equiv \bot$ is not a true proposition. This argument shows that every sound proof system is also consistent.

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Yuval Filmus
  • 279.1k
  • 27
  • 316
  • 512

Your proof system is neither sound nor complete, since $A$ is not a true proposition unless $A \equiv \top$, In which case $\lnot A \equiv \bot$ is not a true proposition. This argument shows that every sound proof system is also consistent.