PLL recognition guide
Jan 4, 2021 · 2 min read · Last updated: Jan 7, 2021
One overlooked aspect of teaching PLL to beginner CFOP solvers in many tutorials online is PLL recognition. Unlike OLL cases that are generally easier to identify, have shorter algorithms and familiar triggers, PLL algorithms are longer and recognizing PLL cases takes a bit of effort. If you are a beginner CFOP learner who knows the basics (2look PLL) and want to learn full PLL and find the task daunting, this guide will help you recognize, learn and practice PLL algs in no time.
Note: This written guide is inspired by badmephisto's PLL Recognition Guide (2009) with improved ordering, terminology and a nice summary at the end. If you prefer learning from video, check out the original guide or watch the video alongside reading this guide.
PLL cases are usually represented by drawing arrows showing which pieces need to swap places. They are named using English alphabets which are chosen to roughly resemble the pattern of these arrows. But that can sometimes be confusing. So to give a simpler and more efficient way, I will completely omit the arrows from visualizations and will go over some basics first.
Out of 21 cases, only 13 are distinct. Other PLLs are either mirrors or inverses. For e.g. Ua perm is the mirror of Ub, meaning if you apply Ua alg to Ub case but by mirroring your moves with the left hand, you'll be able to solve Ub.
The 13 distinct perms are:
 U (Ua, Ub) *
 H *
 Z *
 T (Adjacent corner swap alg in 2look PLL) *
 Y (Diagonal corner swap alg in 2look PLL) *
 F
 E
 V
 A (Aa, Ab)
 J (Ja, Jb)
 R (Ra, Rb)
 N (Na, Nb)
 G (Ga, Gb, Gc, Gd)
* 2look PLL algs
To recognize the rest, we will look whether certain "features" are available. There are 5 main features that are easily noticeable in PLL cases:
1. Headlights
If you see one or more face on the last layer (LL) where two corner stickers have the same color and the middle one has either an adjacent or an opposite color, that's a headlight. 11 out of 21 PLLs have a headlights feature.
A "connected headlight" is when a 1x2 block is connected to a headlight. Depending on the case, there can be either 0, 1 or 2 connected headlights.
PLLs: A, T, R, G (+ H, Z)
Name  PLL  Notes 

A (Aa, Ab)    Adjacent color between headlights
 No connected headlights

R (Ra, Rb)    Adjacent color between headlights
 1 connected headlight

T    Opposite color between headlights
 2 connected headlights

G (Ga, Gb, Gc, Gd)    Ga/Gc  Adjacent color between headlights, Gb/Gd  Opposite color between headlights
 No connected headlights

H    Headlights on all sides
 No connected headlights

Z    Headlights on all sides
 No connected headlights

2. Full bar
A full bar is a 1x3 block of solved pieces on the last layer. Only 5 out of 21 cases have a full bar.
PLLs: J, F, U
Name  PLL  Notes 

J (Ja, Jb)    1 connected bar
 Adjacent colors pair next to bar

F    No connected bar
 Opposite colors pair next to bar

U (Ua, Ub)   
3. Halfbars
Halfbar refers to a 1x2 block of solved pieces on the last layer. 10 PLLs have halfbars in them.
PLLs: J, N, Y, G
Name  PLL  Notes 

J (Ja, Jb)    3 halfbars (+1 full bar)

N (Na, Nb)   
Y   
T   
G (Ga, Gb, Gc, Gd)   
4. 2x2 square
This is just a solved 2x2 block on the top layer. 3 PLL cases have this feature.
PLLs: A, V
Name  PLL  Notes 

A (Aa, Ab)    Has headlights
 Same color in the diagonal corners

V    No headlights
 Different colors in the diagonal corners

5. No features
PLLs: E
The main feature of the E perm is that it has no features. You can look around the last layer and see that there aren't any headlights, full bars, halfbars, or 2x2 squares.
Summary
Name  PLL  Features  Algorithms  Notes 

Aa    Headlights, Adjacent color between headlights, No connected headlights
 2x2 square, same color in the diagonal corners
  x (R' U R') D2 (R U' R') D2 R2
 y x' R2 D2 R' U' R D2 R' U R' x
 R' F R' B2 R F' R' B2 R2
 
Ab    Headlights, Adjacent color between headlights, No connected headlights
 2x2 square, same color in the diagonal corners
  x R2 D2 (R U R') D2 (R U' R)
 y x' R U' R D2 R' U R D2 R2 x
 
Ra    Headlights, Adjacent color between headlights, 1 connected headlight
  (R U R' F') (R U2 R' U2) (R' F R U) (R U2 R')
 R U' R' U' R U R D R' U' R D' R' U2 R'
 y' L U2 L' U2 L F' L' U' L U L F L2
  Parity alg in Old Pochmann method (BLD).

Rb    Headlights, Adjacent color between headlights, 1 connected headlight
  (R' U2 R U2) R' F (R U R' U') R' F' R2
 R' U2 R' D' R U' R' D R U R U' R' U' R
 
T    Headlights, Opposite color between headlights, 2 connected headlights
  (R U R' U') (R' F R2 U') R' U' (R U R' F')
  The most commonly used adjacent corner swap algorithm in 2look PLL.
 Used in Old Pochmann method to solve the edges.

Ga    Headlights, Adjacent color between headlights, No connected headlights
 1 halfbar
  R2 U (R' U R' U') (R U' R2) D U' (R' U R D')
 R2 u R' U R' U' R u' R2 y' R' U R
 
Gb    Headlights, Opposite color between headlights, No connected headlights
 1 halfbar
  y (F' U' F) (R2 u R' U) (R U' R u') R2
 
Gc    Headlights, Adjacent color between headlights, No connected headlights
 1 halfbar
  y2 R2 F2 (R U2 R U2) R' F (R U R' U') R' F R2
 R2 U' R U' R U R' U R2 D' U R U' R' D
 
Gd    Headlights, Opposite color between headlights, No connected headlights
 1 halfbar
  D' (R U R' U') D (R2 U' R U') (R' U R' U) R2
 R U R' y' R2 u' R U' R' U R' u R2
 
Ja    Full bar, 1 connected bar, Adjacent colors pair next to bar
 4 halfbars (including 1 full bar)
  (R' U L' U2) (R U' R' U2 R) L
 y' (L' U' L F) (L' U' L U) L F' L2 U L
 
Jb    Full bar, 1 connected bar, Adjacent colors pair next to bar
 4 halfbars (including 1 full bar)
  (R U R' F') (R U R' U') R' F R2 U' R'
  Used in Old Pochmann method to solve the edges.

F    Full bar, No connected bar, Opposite colors pair next to bar
  (R' U' F') (R U R' U') (R' F R2 U') (R' U' R U) (R' U R)
 
Na     (R U R' U) (R U R' F') (R U R' U') (R' F R2 U') R' U2 (R U' R')
 z U R' D R2 U' R D' U R' D R2 U' R D' z'
 
Nb     (R' U L' U2 R U' L) (R' U L' U2 R U' L)
 R' U R U' R' F' U' F R U R' F R' F' R U' R
  Commonly used diagonal corner swap algorithm in 2look PLL.

Y    2 halfbars, an unsolved corner in between
  F (R U' R' U') (R U R' F') (R U R' U') (R' F R F')
  The most commonly used diagonal corner swap algorithm in 2look PLL.
 Altered Y Perm (without the F moves at the beginning and the end) is used in Old Pochmann method to solve the corners.

V    2x2 square, different colors in the diagonal corners
  (R' U R' U') y (R' F' R2 U') (R' U R' F) R F
 
E     x' (R U' R' D) (R U R' D') (R U R' D) (R U' R' D') x
 
Ua     (R U' R U) R U (R U' R' U') R2
 
Ub     R2 U (R U R' U') R' U' (R' U R')
 
H     
Z     (M2 U M2 U) (M' U2) (M2 U2 M')
 
This is just a beginner's guide to PLL recognition. There are advanced techniques that can help you recognize PLL by looking at just 2 sides of the last layer. Check out the links below to learn more.
Further reading and credits