Focusing on one preparational move

 What do I try to accomplish?

I want to develop a reasoning system that makes optimal use of the pruning capabilities based on value and logical reasoning. I reckon that it is universal, so that when I develop it to attack the queen, the same reasoning method can be used to attack a rook. That way, you can rule out whether there is a tactic in the position or not by just applying the reasoning system from the king down to the knight.

I'm not bothered by the fact that the reasoning system might get bulky, because it tells me which parts I must absorb by System 1. I'm not bothered by how long it takes, since there are only 20 scenarios to learn. The position below has already 4 of them. That is already 20%!

To prevent to become overwhelmed, I divide the tasks in many little subtasks. While fiddling around with the smallest task possible, I am surprised how much hidden details gets unearthed along the way.

White to move

3r3k/nb2q1pp/p4p2/Np2p3/4P3/2P2N1P/PnB1QPP1/R5K1 w - - 0 1

We have already seen this position before. We already ruled out the king as potential target. We now that the queen is not going to be trapped anytime soon, so IF the queen is the target to aim for then she must be at the receiving end of a duplo attack.

We already know that the queen is not on het target square, but how can we find that out by systematic reasoning?

We can first ask: if the queen is on the target square, then what would be the second target? And what would be the attacker?

Q and R can be attacked by Nc6. Since the A:D-ratio of c6 is not BAD enough, we can rule that out.

So we arrive at: the Queen is not on the target square. There are a few standard scenarios to transfer a piece to its target square: push (chase) and pull (lure). 

Since the Queen has too much space, she can't be chased. But she can be lured to b7 by capturing the bishop. We can't possibly know whether b7 is one target of a duplo attack or not. Since I split the investigation up in subtasks, that is something for another post.

We can formulate it in other words too: the Queen is a defender of the target b7.

While fiddling around with the position, some details were unearthed.

When I put the black rook on e8 instead of d8:

White to move

Now black can postpone the recapture of b7 because the white knight has no safe withdraw route from b7:

1.Nxb7 Nc4

The difference is that the white knight has no additional threat on Rd8.

This leads to two additions to the scenarios:

• proposed rule: a capture with a threat is preferred above a capture without an additional threat.
• beware of a safe withdrawal of the attacker after the combination