# Notcher Code

Difficulty: Intermediate   Keywords: Life & Death

On this page we devise a coding system for notchers, in order to set up a systematic approach to their life and death status.

Suppose the notcher is black and the surrounding group white.

Notcher 112NS = nabxy

Below squared stones (): notch (n)

Circled stones (): legs (ab)

Cross marked (): hips (xy)

1. The notcher has a notch of n spaces on the second line.
2. The notcher has a left leg of length a and a right leg of length b. The legs are the (black) stones on the second line.
3. The notcher has a degree of weakness, x on the left hip and y on the right hip:
• The letter W means that the hip is white (weak or an (angle) wedge),
• N means that the stone on the hip is absent (neutral),
• while S means that it is black (solid or strong).

We put this information into a code nabxy, where n, a, b take numerical values, and x and y can be either W, N or S.

The status of the notcher assumes no outside liberties and no escape threat (e.g. a descent that threatens to live and to escape). That would have to be covered by a second status in parentheses or the like.

The code is leg-normal if

• a < b or
• a = b and x <= y (W < N < S: weaker before stronger)

It is hip-normal if

• x < y or
• x = y and a <= b

Use leg-normal if you put up a page. Use hip-normal if you search in the Table of Notchers (that gives tables of reasonable size). A flip might be necessary: an exchange of a and b as well as x and y.

See Table of Notchers for lots of examples.

Notcher Code last edited by hnishy on January 19, 2023 - 06:52