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5 votes

Analogy between Gödel's incompleteness proof and Richard's argument

Both examples are instances of diagonalization, a technique also used to prove Cantor's theorem ($\kappa < 2^\kappa$ for all cardinals $\kappa$) and Turing's theorem that the halting problem is undeci …
Yuval Filmus's user avatar
2 votes

Why does soundness imply consistency?

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 e …
Yuval Filmus's user avatar
5 votes
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Understanding of Turing's Answer to the Entscheidungsproblem

For example, it won't be able to prove its own consistency (this is Gödel's second incompleteness theorem). (A proof system is consistent if it doesn't prove a statement and its converse.) …
Yuval Filmus's user avatar