What is a radical

A radical is a named tuple of constraints that defines a BJJ position. Two layers, two primitives.

Radical = Frames + CONs
             |        |
             |        |-- required  (must exist)
             |        |-- forbidden (must not exist)
             |        '-- forbidden_bilateral (must not both exist)
             |
             '-- facing, ground state
Frames

Global spatial facts about the two bodies. Four types:

FacingOpposed FacingAligned OnGround(X) NotOnGround(X)
CON

One wrapping contact between two limb axes. 9 independent fields:

Attacker role part sign dir
Axis role part sign dir
Wrap helicity

Two primitives, one data type for contacts, three quantifiers over it.

Defense lines

Guard players defend through three barriers. Each level cleared brings the passer closer to a dominant position.

Level 3
Feet
OGRD — DLR, SLX, RDLR, LSSO, OMOP

First line of defense. Feet and legs create distance, hooks, and entanglements.

Level 2
Knees
HGRD

Feet cleared. One knee entangles the opponent's leg — half guard.

Level 1
Hips
CGRD

Last barrier. Both legs wrap the torso, feet locked. Closed guard.

Level 0
Passed
MNT, SCTR, BCTR, TRTL

Guard passed. Dominant positions: mount, side control, back control, turtle.

Structural distance

How it works

Each radical is defined by frame constraints and CON primitives. A CON has 9 independent fields: attacker role, part, sign, direction; axis role, part, sign, direction; helicity.

Distance = number of fields that differ. One field change = one structural edit.

Adding a contact

An unmatched CON costs 9 — the number of independent fields. Going from no contact to a specific contact means specifying all 9 fields from nothing.

The chain

Each step is exactly one field change:

DLR helicity SLX ax_part LSSO ax_dir OMOP

Distance matrix — 7 fundamental positions

MNTSCTRBCTRCGRDOGRDHGRDTRTL
MNT ·291312201335
SCTR29·2739302418
BCTR1327·19312429
CGRD123919·302343
OGRD20303130·930
HGRD132424239·26
TRTL351829433026·

Distance matrix — open guard subtypes

OGRDDLRSLXRDLRLSSOOMOP
OGRD·1111111111
DLR 11·1123
SLX 111·212
RDLR1112·34
LSSO11213·1
OMOP113241·

Transitions

Pass / Advance
OGRD→HGRD, OGRD→SCTR, HGRD→SCTR, CGRD→SCTR, CGRD→MNT, SCTR→MNT, SCTR→BCTR, TRTL→BCTR
Recover / Escape
SCTR→HGRD, SCTR→OGRD, SCTR→TRTL, MNT→OGRD, MNT→HGRD, BCTR→TRTL, BCTR→OGRD, TRTL→OGRD
Close guard
OGRD→CGRD, HGRD→CGRD
Lateral (subtype switch)
DLR↔SLX, DLR↔RDLR, SLX↔LSSO, LSSO↔OMOP