types 1,2 are found there

A third type of hidden unique rectangle is plausible:

- Code: Select all
`*---------------------------*`

|A-B . AB | . . . | . . . |

|/ . . | . . . | . . . |

|/ . . | . . . | . . . |

|-----------+-------+-------|

|/ . . | . . . | . . . |

|AB+ \ -AB+| \ \ \ | \ \ \ |

|/ . . | . . . | . . . |

|-----------+-------+-------|

|/ . . | . . . | . . . |

|/ . . | . . . | . . . |

|/ . . | . . . | . . . |

*---------------------------*

where AB+ = a cell with extra candidates

\ = no candidates for B

/ = no candidates for A

R1C1 <> B

R5C3 <> A,B

A 4th type of hidden unique rectangle is plausible:

- Code: Select all
`*---------------------------*`

|A+-B . AB | . . . | . . . |

|/ . . | . . . | . . . |

|/ . . | . . . | . . . |

|-----------+-------+-------|

|/ . . | . . . | . . . |

|AB+ \ B-A+| \ \ \ | \ \ \ |

|/ . . | . . . | . . . |

|-----------+-------+-------|

|/ . . | . . . | . . . |

|/ . . | . . . | . . . |

|/ . . | . . . | . . . |

*---------------------------*

where AB+ = a cell with extra candidates

\ = no candidates for B

/ = no candidates for A

R1C1 <> B

R5C3 <> A