Suppose we have two completed grids.

Suppose that for a certain digit k, when we look at all positions of k within the first grid, the same positions in the second grid contain 1-9 uniquely.

Then one could say that digit k of the first grid reveals a group in the second grid.

Two grids with similar relationships could then be called revealing twins.

I've created two puzzles based on the following revealing digits:

1 in the first grid reveals a group in the second grid

9 in the second grid reveals a group in the first grid

Example of how to apply these constraints:

- Code: Select all
`1..|...|... 2..|...|...`

...|...|7.. ...|...|9..

...|...|... ...|...|...

---+---+--- ---+---+---

.1.|...|... .?.|...|...

...|...|... ...|...|...

...|...|... ...|...|...

---+---+--- ---+---+---

..?|...|... ..9|...|...

...|...|... ...|...|...

...|...|... ...|...|...

In the second grid R4C2 <> 2. In the first grid R7C3 <> 7.

Revealing twin 1:

http://www.scrybqj.com/images_diversen/ ... ns_no1.pdf

Code lines:

- Code: Select all
`000309600008000000070462050309048010005000000000000030000000000000800009902010000`

080000000005970000047000002700604000003000000600090100064007028000003704000000003

Revealing twin 2:

http://www.scrybqj.com/images_diversen/ ... ns_no2.pdf

Code lines:

- Code: Select all
`010000007298001000000960000003006000000000082001008600000209014300000700000080000`

003900000090458007000000040280000000071080400000000500000000060000100203008020001

These puzzles should be solvable with singles, pairs, triples, ... and also locked candidates and pointing pairs.

I'm still looking for an example grid with two revealing dgits in both directions (or the computer will while I'm asleep).