Let me try to answer to your post in my way.

First of all this is an exocet our friend totuan had something else in mind when he wrote "almost exocet"

The exocet base logic is very simple and widely open.

Take 2 cells in the same unit containing n possible digits. This is the base

Take 2 other cells anywhere this is the target

If for any digit of the base one target cell must contain this digit then we have an exocet

the target can only contains digits form the base

For any pair in the base, we have the same pair in the target

This is the trivial base rule.

The 2 target cells can be replaced by 3 target cells having a locked digit ....

For a manual player, an exocet is of interest if it can be easily seen and if it has good chances to bring some solving tools.

The first reduction is to have an exocet located in a band with, usually the base in one mini row and the targets in the 2 other boxes.

The second reduction is to have an easy proof of the digit per digit constraint. For me, the proof is easy when for each digit it comes from the digit pm.

The exocet here fits with these reductions. So if you suspect that you have a potential exocet, You can apply the simple proof

champagne wrote:Step 1 check that this is an exocet pattern for each digit:

a) force the digit in the base

b) clear the digit in the target

c) check that you have no solution

BTW, when you have a locked digit, "platinum blonde" as example, the proof is very similar, point b) is clear the digit in the 3 target cells

David made a huge work to define the subset Jexocets where the exocet property can be derived easily from the given. With my computer, I stick to the general definition (restricted normally within a band) so I let him comment on the Jexocet.

Next step is the solving rules offered by an exocet.

Again, we have an open space with the basic logic. If a cell sees both target (/all targets), it can not contain the base digits.

A more specific clearing rule has been seen using a UR threat (see "abi loop" in the documentation)

And many more specific derived rules have been written here and there.

In our example 2 basic cleaning moves have been done

If the base contains the digit 4, then both targets would contain the digit 4, no pair can be valid with the digit 4.

The second is just a consequence of the basic properties applied to the box 1 pattern.

the cell r1c3 sees the 2 targets and contains only the 3 digits of the base

the cell r3c1 sees the base and r1c3

r3c1 can not contain the base pair (sees the base)

the third digit is forced in r3c1

so r3 c1 can not contain any of the base digits