Further theory of ecto-battery

On the announcement page of 28th TT CCM there is a short outline of ecto-battery. While the "normal" cases are easy to understand, naturally there are many fringe cases using various fairy elements. That is why a few interested composers have asked for clarifications, whether some specific cases are ecto-battery or are not.

Let's give first the definition of battery:

The battery is a configuration of two pieces A (front), B (rear) and square X initially not attacked by B along some line*. The departure of piece A from its square activates piece B to square X, without specific needs for activity of A. (In orthodox chess, A stands on the line in question between B and X.)

Now the anti-battery:

The anti-battery is a configuration of two pieces A (hurdle), B (rear - jumping piece) and square X initially not attacked by B along some line*. The arrival of piece A on specific square activates piece B to square X, without specific need for activity of A. (In a case B is grasshopper, A arrives on the line between B and X, next to X.)

And finally the ecto-battery:

The ecto-battery is a configuration of two pieces A (moving), B (rear) and square X initially not attacked by B along some line*. The move of piece A activates piece B to square X, without specific need for activity of A and without departing from nor arriving to line in question.

* - It is important to realize, that the line in question is not necessarily usual straight line, horizontal, vertical, diagonal etc. It is understood in the loose sense, it might be curved line, e.g. of a rose, or more complicated fairy line as you can imagine, e.g. capture by white Pe3 on d4 in Anticirce is played along the unusual line e3-d4-d2.

So now I will give a few example with explanations as I do understand the ecto-battery. It is by no means a final word on this subject, rather the current status - how the judge probably will be considering the entries. I would be happy if any more experienced theoretician would build more precise theory.

Also, so far I have seen the following fairy elements used for showing ecto-battery: locust (and its relatives, including marine pieces), Anticirce (almost the whole family of Anticirces, to be precise), Kamikaze (with convention that the move of capturing piece continues and ends out of board, just like "raus" move in Dynamo Chess), hopping pieces + Circe (with rebirth on that way activated hopper line), Take&Make (by some experts considered to be a kind of Anticirce, but usually not treated as such).

My thanks go to Dmitry Turevski, Gilles Regniers and Manfred Rittirsch for providing some positions and food for thought.

Here the move in question is 1.Qxh8(Qd1)+. In the initial position white nightrider does not check bK and the queen move goes from e5 to d1 via h8. Removing black rook from h8 along the way activates line b3-h6-h8. Clear example of ecto-battery.









(2+2)
Anticirce
nightrider b3

Two checking moves by white rook can be considered.

1.Re7+ checks by unparalyzing Bf8, by closing line. Clearly it is arrival effect of the rook move that plays the crucial role, so we have here a kind of anti-battery.

1.Rxa3+ also checks by unparalyzing Bf8, by capture of Ba3. It is again arrival effect of the rook move that plays the crucial role, so we have here another kind of anti-battery.









(2+2)
Madrasi

Two checking moves by white bishop can be considered.

1.Bh3 checks by allowing capture of bK by white rook, by closing line of Rh1 aimed at bK, so that it is again a case of anti-battery.

Similarly to the previous diagram, 1.Bxh1 is the case of anti-battery too.









(2+2)
Isardam

Now it becomes more difficult. Let's consider why Kh7 is not checked in the diagram position. Apparently Nf8 checks bK, but in fact it cannot capture the king by 1.Nxh7(Nh8)?? as that would lead to illegal paralysis of two nightriders along b5-h8 line.

Now move 1.Rd6+ cuts the line in question, making the capture by wN legal. Arrival effect - anti-battery.

The capture 1.Rxb5(Rh1)+ is however an ecto-battery - it makes check possible by passing through the prolonged line f8-h7-h8-b5. Complicated case.









(3+2)
Anticirce Isardam
1+1 nightrider

As in the previous case, Nf8 cannot capture bK due to ensuing illegal paralysis of nightriders. Well, not two-way paralysis as Nb5 would not be able to capture Nh8, so that Nh8 would not be captured. But Nh8 could capture Nb5... still illegal.

And what about 1.Sb8+? Yes, the check sign is well placed as arrival of knight on b8 makes also the other way of paralysis impossible and thus allows capture of bK by wN. Nice, but not ecto-battery.









(3+2)
Anticirce Isardam
1+1 nightrider

Final joke... sorry, final scheme to consider for now.

In the initial position joker a1 naturally does not check black king. Hovewer any move of white rook activates white joker to have the rook mobility. Is e.g. 1.Rh6+ an ecto-battery? It is not. Although the joker is activated without any need to resort to any specific departure or arrival square of rook move, the problem is this time with the requirement of specific movement ability of potential piece activating the ecto-battery.









(2+1)
joker a1

Comments to Juraj Lörinc.
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