# Halt halt halt

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Designed by | Hakerh400 |
---|---|

Appeared in | 2020 |

Computational class | Turing complete |

Major implementations | Unimplemented |

File extension(s) | `.txt` |

**Halt halt halt** is a Turing-complete brainfuck derivative which can partially solve the Halting problem.

## Overview

Besides all 8 instructions inherited from brainfuck, *Halt halt halt* has an extra instruction: `?`

That instruction does the following:

- Interprets the current output (that is generated so far) as a
*Halt halt halt*program (it is an error if the program has unmatched brackets) - Resets the output (the output becomes empty)
- Tries to determine whether the parsed program will halt on empty input using ZFC axioms

Based on the result of step 3, do the following:

- If it can be proved that the program halts, do nothing
- If it can be proved that the program does not halt, increment the current cell by
`1`

- If it is undecidable (independent of ZFC), increment the current cell by
`2`

- If ZFC is inconsistent, increment the current cell by , where is an integer such that (the value of is implementation dependent, it can even be chosen randomly)

After this continue execution normally.

## Properties

*Halt halt halt* is similar to Hyperon, but while Hyperon is uncomputable (because it assumes the existence of a perfect (consistent) first-order logic system), this language is Turing-complete, because instruction `?`

may never finish if ZFC is consistent (and the consistency of ZFC cannot be proved from within ZFC itself, as stated by the Gödel's Second incompleteness theorem).

## Interpreters

Unimplemented.