PLL Recognition Trainer
Identify the PLL from just two sides.
What is two-sided PLL recognition?
Two-sided PLL recognition means naming which of the 21 PLL cases you are looking at from only the two sides you can see - front and right - without rotating the cube to peek at the back. Every PLL case can be identified this way: the six visible stickers always carry enough information, which is why fast solvers never spend time turning the cube to inspect the last layer.
Recognition works by scanning for a small set of patterns in a fixed order of precedence: 3-bar → lights → 2-bar → bookends.
- 3-bar - a whole side of one color (corner, edge, corner all matching).
- Lights (headlights) - two corners of the same color with a different-colored edge between them.
- 2-bar - a corner and its adjacent edge sharing one color.
- Bookends - the two outermost stickers of the six you see matching each other.
Choose the first pattern that matches, from the nine pattern groups below, and within that group find the first case that matches. Color rules are always relative, not absolute: "opp" means opposite and "adj" means adjacent, relative to the nearest pattern color. Each case appears in four color combinations and may be mirrored, so learn the patterns rather than memorizing specific colors.
The trainer above drills exactly this skill: it shows a random PLL case at a random angle with only two sides visible, you name the case, and it tracks your speed and accuracy per case. The confusion matrix further down reveals which cases you mix up, and the weighting sliders steer practice toward your weakest ones.
Pattern system from the two-sided recognition guide by Mark Rivers.
Cases
Filter which cases the trainer above draws from. Your selection is saved for next time.
Tune how often each case comes up
Factors
Higher means that factor pulls more of the practice toward it. Set everything to zero for a plain even shuffle.
Favour cases you've marked Don't Know or Learning over ones in muscle memory.
Favour cases you get wrong more often.
Favour cases that take you longer to recognise.
Resulting chances
Probability each case is the next one shown .
3-Bar
Double Lights
Lights + 2-Bar
Lone Lights
Double 2-Bar
Outside 2-Bar
Inside 2-Bar
Bookends No Bar
No Bookends
Statistics
Per-case recognition (average of last 10 attempts)
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
Gb/d by OPPOSITE LIGHTS
J by DOUBLE 2-BAR
A by DOUBLE 2-BAR
R & Ga/c by BOOKENDS
F by CHECKERS
Frequently asked questions
- Can every PLL case really be recognized from two sides?
- Yes. Any two adjacent sides show six stickers, and that is always enough to pin down the case - the pattern hierarchy (3-bar, lights, 2-bar, bookends) plus the relative colors distinguishes all 21 PLLs at every angle. No cube rotation needed.
- How do I get faster at PLL recognition?
- Learn the patterns instead of memorizing color pictures - bars, lights and bookends stay the same across all four color combinations of a case. Then drill deliberately: the confusion matrix above shows exactly which case pairs you mix up, and raising their weight puts them in front of you more often.
- Is this a PLL algorithm trainer?
- No - this trainer is about naming the case fast, which is its own skill. For the algorithms themselves, ranked by how often top solvers actually use them, see the PLL algorithm database.
- Do I need to know all 21 PLL algorithms first?
- No. Recognition and algorithms can be learned side by side - use the case filters above to train only the cases you know so far. If you are still on 2-look PLL, recognizing corner permutation from two sides transfers directly once you go full PLL.