Two-Sided PLL Recognition
- Look for these features in order of precedence: 3-bar → lights → 2-bar → bookends.
- Choose the first pattern that matches, from the nine patterns below, and within that group find the first case that matches.
- Remember that there are four color combinations for each case, and cases may also be mirrored.
- Color rules are relative: "opp" = opposite, "adj" = adjacent, relative to the nearest pattern color.
Guide by Mark Rivers.
3-Bar
U — headlights
J — 2-bar (orange)
J — 2-bar (blue)
F — 4 colors
Double Lights
Z — 2-color 6-checker
Z — adj edges & 4 colors
H — opp edges
U — 2:1 pattern & 3 colors
Lights + 2-Bar
T — inside bar & 3 colors
R — inside bar & 4 colors
A — outer bar & 3 colors
Ga/c — outer bar & 4 color
Lone Lights
R — 5-checker
Ga/c — 4-checker
Gb/d — lights enclose opp
A — lights enclose adj (but no checker)
Double 2-Bar
Y — both outside
A — both inside & bookends
V — inside & no bookends
J — same side & bookend
N — same side & no bookend
Outside 2-Bar
V — no bookend
R — adj appears twice
Gb/d — opp appears twice
T — adj by bar & 4 colors
A — opp by bar & 4 colors
Inside 2-Bar
Ga/c — bookends adj color
Gb/d — bookends opp col
Y — no bookends
Bookends No Bar
F — enclosed 4-checker
R — adj appears twice
Ga/c — opp appears twice
No Bookends
V — inner 4-checker
Y — outer 4-checker
E — 5-checker w/ opp middle
Which way to AUF?
Once you've identified the case, the AUF direction is usually obvious from the visible faces. For the trickier cases, these hints disambiguate. Which exact AUF you do still depends on the algorithm you use.
U by 2:1 PATTERN
if odd edge opp color, 3-bar is adjacent
if odd edge adj color, 3-bar is opposite
Gb/d by OPPOSITE LIGHTS
J by DOUBLE 2-BAR
A by DOUBLE 2-BAR
R & Ga/c by BOOKENDS
R — lights further from test pair
Ga/c — lights nearer to test pair