Monitoring the time

 Forcing tactics are based on space (trap, mate) or time. It is important to know how "time" looks like, in a position.

Time can originate from two sources: a B.A.D. (Barely Adequate Defended) piece or a multi function move. Let us see whether we can clarify these vague descriptions. The goal is to get some sort of definitions that simplify matters and reduces the chance of confusion.

BAD

The term B.A.D. (Barely Adequate Defended) piece is originally coined by CM Dan Heisman, if I remember well.

What we want is a term for targets that are currently under attack, but where the balance of attack and defense is equal. Why are BAD pieces interesting?

If we can disturb the delicate balance between attackers and defenders, the BAD piece all of a sudden becomes a ripe fruit, ready to pluck. We need to:

• change the balance of attackers:defenders
• pluck the fruit

Where does the time come from? With a BAD piece, we already have the attacker in place. When we harass the defender, the opponent must all of a sudden answer two attacks:

• the attack on the defender
• the attack on the target which is no longer defended

White to move

Re6 is BAD [1:1]. By Rxg7+ the defender of Re6 is annihilated. "The time doubles". That is, all of a sudden black must do two tasks with one move:

• Answer the exchange of Rxg7+
• Save the rook on e6 which is deprived from its defender

In a sense, eliminating the defender is a multi purpose move.

The reason for identifying BAD pieces, is that there is already one attack in place, so you only need to add another one. By eliminating the defender, you change the balance of attack on the target AND the elimination of the defender needs an answer.

I add extra limitations to the BAD piece:

• it must be currently under attack
• it must be a piece, not a square

I don't know whether I am going to use these limitations or not. But for now it seems appropriate to prevent confusion. Terminology and definitions are not casted in concrete.

Under-defended

If a piece can be barely adequate defended, there must be three states of a piece that is currently under attack:

• inadequate defended = NOT defended
• barely adequate defended = BAD
• adequate defended = defended

White to move

• Rc5, Bd2 are NOT defended
• Bd6 is BAD
• Bf2 is defended
• Ba1 is NOT under attack currently (LPDO)

Implicitly, the value of the attacker, target and defender is incorporated in this terminology. Both Rc5, Bd2 are considered to be NOT defended.

The terminology has time incorporated too. For to pluck Rc5 or Bd2, just one tempo is needed, for Bd6, you need two tempi (you must eliminate the defender first), while Bf2 in unpluckable, right now.

Multi purpose moves

Looking for BAD pieces is a way to start the logic and to trace the track to the defenders where the tempi can be gained. But sometimes, there are no BAD pieces.

In the position below there is no BAD piece. So we can't start our investigation there.

White to move

4rrk1/pppq2b1/3p2Qp/3P1bp1/2PpN3/1P1B2P1/P4P1P/R3R1K1 w - - 0 1

Hence we must look at another way "to double the time". We have to look for multi purpose moves.

There are two evident batteries in the position:

• Bd3 and Ne4 can deliver a discovered attack against Bf5
• Re1 and Ne4 can deliver a discovered attack against Re8

Is there a useful square where the knight can go?

Nf6 delivers a triple attack on:

• The King, which is undefended by default
• The Queen which is undefended
• Rook e8 which is undefended

According to the terminology I introduced. Furthermore Qg6 delivers a pin on Bg7 and the black King (Fun) already. With one move Nf6 white attacks 4 targets. 

There are are two answers for black:

• Rxf6
• Kh8

None of these addresses all 4 threats.

I hold a plea for the following approach. Start your logic at the beginning: BAD piece or multi function move. There is no need to think about your queen which is under attack. Only when your logic indicates that your plan fails because black has an adequate answer, it is time to worry about your queen.