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[Help Thread] Petrus Discussion and Help thread

xyzzy

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Dec 24, 2015
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1,701
Merely looking at the written solve, the one thing that stands out immediately is that the solutions are very long. I normally expect each line/step to be 5-10 moves, with the exception of last layer algs. Point by point breakdown, starting from the scramble. Blue text indicates your solve, red text indicates my suggestions.

1. This scramble has no pre-made pairs at all, so it's not clear which colours one should use to build the initial 222 block. I see that the blue-yellow-red corner can join with either the blue-yellow edge or the red-yellow edge in one move, and there's also two correctly permuted cross edges on the blue face. Try for example:
x L2 // corner-edge pair
(U' D') // two 2×2×1 blocks
R' // join the blocks to get a 2×2×2


2. L' U' // edge
Two moves for a single edge is very inefficient, considering there are already multiple free/1-move edges all over the cube. Make use of edge-centre pairs when they show up (and they show up very often), but don't go out of your way to make them. Also, since you're following this up with a z2 rotation, you can also rotate first, executing it as z2 R' D' instead.

3. It looks like you're trying to solve the 222 block by doing a half-cross and then inserting an F2L pair.
F U' F' R U' R2 U' R' // insert white-orange
F' U' F U2 F' U F // white-green-orange F2L slot

Don't do this. (I don't know how to solve this specific situation well either, but I wouldn't have chosen this block anyway. Herein lies a strength of Petrus and other blockbuilding methods: you don't have to know how to solve every situation well, because 99% of the time you can just choose a different, easier starting block.) Even if you wanted to do it half-cross-then-slot, it would've been better to rotate to solve the F2L slot rather than use so many F moves in succession.

4.
y' F2 // white-red edge
L2 U L' U' R U R' // white-red-green F2L slot

Again, a CFOP-y approach, but here I don't see anything else obvious so this is acceptable.

5.
y2 U F' U' F R2 U2 F' U' F // EO
I would've just done a y' rotation, so that edge orientation can be done with R U* R' / L' U* L / R' F* R / L F* L' triggers, which are better than F' U* F and B U* B' triggers. Anyway, this EO case can be done in 5 moves:
y2 F R2 F2 U F
The five-move solution is very awkward to execute from this angle (orange in front), but if you'd done a y' rotation instead of a y2, it'd be like this:
y' Rw U2 Rw2 F Rw
Way better. I think you mostly just need to familiarise yourself with how to fix bad edges, because it looks like you're using only F' U' F to flip the UL and FR edges, when there are many other ways to flip two edges.

6.
U' R2 U R2 U' R U' R' U R // white-red-blue F2L slot
U R U R' U2 R U R' // white-orange-blue F2L slot

Not sure what the initial U' is for. I guess you were trying to influence the next slot, which isn't a bad idea in general, although this is pretty tricky and in this specific case, it just replaced a 7-move last slot case with another 7-move last slot case. Other than the initial U', this is fine, although you can also look at other ways to solve a square on the right face, e.g.
R' U' R' U2 R' U' R2 // white-orange-blue square, then
R U2 R2 U' R2 U' R' // white-red-blue slot


7.
y' F U R U' R' U R U2 R' U' R U R' F' // COLL (you typoed the rotation)
U M2 U' M U2 M' U' M2 U // EPLL

Do not ever do y rotations during the last layer. Rotations are a lot slower than AUFing. Other than that, this is fine, although I'm a bit concerned about why you know COLL when you're still having trouble with general efficiency.
 
Last edited:

ShadowCurv

Member
Joined
Jun 22, 2018
Messages
9
Merely looking at the written solve, the one thing that stands out immediately is that the solutions are very long. I normally expect each line/step to be 5-10 moves, with the exception of last layer algs. Point by point breakdown, starting from the scramble. Blue text indicates your solve, red text indicates my suggestions.

1. This scramble has no pre-made pairs at all, so it's not clear which colours one should use to build the initial 222 block. I see that the blue-yellow-red corner can join with either the blue-yellow edge or the red-yellow edge in one move, and there's also two correctly permuted cross edges on the blue face. Try for example:
x L2 // corner-edge pair
(U' D') // two 2×2×1 blocks
R' // join the blocks to get a 2×2×2


2. L' U' // edge
Two moves for a single edge is very inefficient, considering there are already multiple free/1-move edges all over the cube. Make use of edge-centre pairs when they show up (and they show up very often), but don't go out of your way to make them. Also, since you're following this up with a z2 rotation, you can also rotate first, executing it as z2 R' D' instead.

3. It looks like you're trying to solve the 222 block by doing a half-cross and then inserting an F2L pair.
F U' F' R U' R2 U' R' // insert white-orange
F' U' F U2 F' U F // white-green-orange F2L slot

Don't do this. (I don't know how to solve this specific situation well either, but I wouldn't have chosen this block anyway. Herein lies a strength of Petrus and other blockbuilding methods: you don't have to know how to solve every situation well, because 99% of the time you can just choose a different, easier starting block.) Even if you wanted to do it half-cross-then-slot, it would've been better to rotate to solve the F2L slot rather than use so many F moves in succession.

4.
y' F2 // white-red edge
L2 U L' U' R U R' // white-red-green F2L slot

Again, a CFOP-y approach, but here I don't see anything else obvious so this is acceptable.

5.
y2 U F' U' F R2 U2 F' U' F // EO
I would've just done a y' rotation, so that edge orientation can be done with R U* R' / L' U* L / R' F* R / L F* L' triggers, which are better than F' U* F and B U* B' triggers. Anyway, this EO case can be done in 5 moves:
y2 F R2 F2 U F
The five-move solution is very awkward to execute from this angle (orange in front), but if you'd done a y' rotation instead of a y2, it'd be like this:
y' Rw U2 Rw2 F Rw
Way better. I think you mostly just need to familiarise yourself with how to fix bad edges, because it looks like you're using only F' U' F to flip the UL and FR edges, when there are many other ways to flip two edges.

6.
U' R2 U R2 U' R U' R' U R // white-red-blue F2L slot
U R U R' U2 R U R' // white-orange-blue F2L slot

Not sure what the initial U' is for. I guess you were trying to influence the next slot, which isn't a bad idea in general, although this is pretty tricky and in this specific case, it just replaced a 7-move last slot case with another 7-move last slot case. Other than the initial U', this is fine, although you can also look at other ways to solve a square on the right face, e.g.
R' U' R' U2 R' U' R2 // white-orange-blue square, then
R U2 R2 U' R2 U' R' // white-red-blue slot


7.
y' F U R U' R' U R U2 R' U' R U R' F' // COLL (you typoed the rotation)
U M2 U' M U2 M' U' M2 U // EPLL

Do not ever do y rotations during the last layer. Rotations are a lot slower than AUFing. Other than that, this is fine, although I'm a bit concerned about why you know COLL when you're still having trouble with general efficiency.
Thanks for the help! I will keep this in mind when solving. I know COLL because I learned CLL for 2 by 2 and figured it would be more productive if I would learn them both at once, and some algs are faster for me to execute. I did end up learning all the different algs though.
 

xyzzy

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Joined
Dec 24, 2015
Messages
1,701
I'm just going to go through my splits first:2x2x2- 5 to 8 secs, yay ; 2x2x3- 12 secs ish, eek; EO- 2 to 5 secs, OK; Finish F2L- 10 to 13 secs, OK and finally LL- 10 secs, yay.
When you look at these, I think you can spot the problem... My 2x2x3 is abysmal. Seriously. I can understand the basic technique of building the 2x2x1 to swing into the main block, but cannot execute it properly. Petrus' web says to build it like your 2x2x2, but I 'm so bad at finding pieces, making the pair, then finding another piece if I've lost track of it and then building the 2x2x1. This is eliminated on my 2x2x2 because I can use the technique well and the inspection time, but obviously I cannot stop and look halfway through my solve for 15 secs. It would be nice if anybody could explain to me EXACTLY how they build their 2x2x2
Also, when I ask how fast you can do your 2x2x3, I meant your EXTENSION. Go back and change if you misunderstood.
The first two steps of the Petrus method take me about 2.4 and 3.0 seconds respectively. It's probably normal for the extension step to take a bit longer because you don't have 15 seconds of free planning time to use, but one way of working around this is to try to track the pieces needed for the square as you solve the initial 2×2×2 block so you don't waste 2+ seconds trying to find them or to decide which of three directions to extend the block.
 

PetrusQuber

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2020XIEC01
I started dedicated cubing like half way throught May, and started off using Petrus. Once I'd learnt it, I got lots of sub 3 min solves until I finally managed to break the sub 1 min barrier with practise and lots of looking through websites. That was in June. 1 month later, I got my first sub 45 solve, and then got stuck sround there. (I managed some dips to around sub 40 which would last like a day before rising again.)
Is this normal, or am I improving faster or slower than usual, because I would like a goal.
 

efattah

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Feb 14, 2016
Messages
534
As long as you are improving at all, that is awesome. Many people stop improving around 15-20 seconds even if they practice a lot. So enjoy every PB.
 

Tabe

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I started dedicated cubing like half way throught May, and started off using Petrus. Once I'd learnt it, I got lots of sub 3 min solves until I finally managed to break the sub 1 min barrier with practise and lots of looking through websites. That was in June. 1 month later, I got my first sub 45 solve, and then got stuck sround there. (I managed some dips to around sub 40 which would last like a day before rising again.)
Is this normal, or am I improving faster or slower than usual, because I would like a goal.
I went 6 months without setting a new PB. In the last 6 weeks, I've beaten that old PB at least 10 times. Sometimes you hit a plateau and it just takes time to break through it.
 

PetrusQuber

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my house, cubing.
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As long as you are improving at all, that is awesome. Many people stop improving around 15-20 seconds even if they practice a lot. So enjoy every PB.
Ok sure-I just got a PB of 34 secs :)
I went 6 months without setting a new PB. In the last 6 weeks, I've beaten that old PB at least 10 times. Sometimes you hit a plateau and it just takes time to break through it.
Lol. I'm just trying to improve as fast as I can to get to sub 30, (and yeah, I'll probably meet plateaus) and sometimes I get frustrated with my progress, because this summer is probably going to be the only cubing time I get for a while. I think I'm going to do some focused practising with my extensions to 2x2x3 and EO and also learn my full PLL.

Btw you guys, for some reason, my improvements are made in leaps, so I won't improve like by 2 seconds a week, I'll be like, on sub 1 min, and suddenly drop to sub 55 one day.
 

efattah

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Feb 14, 2016
Messages
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Ok sure-I just got a PB of 34 secs :)

Lol. I'm just trying to improve as fast as I can to get to sub 30, (and yeah, I'll probably meet plateaus) and sometimes I get frustrated with my progress, because this summer is probably going to be the only cubing time I get for a while. I think I'm going to do some focused practising with my extensions to 2x2x3 and EO and also learn my full PLL.

Btw you guys, for some reason, my improvements are made in leaps, so I won't improve like by 2 seconds a week, I'll be like, on sub 1 min, and suddenly drop to sub 55 one day.
Improvements usually come in jumps, and are often spread out with areas where your times are worse. Most of the time you learn anything new, your times get worse because your speed on the new tricks is very slow. Then eventually everything gets smooth and you get some PB jumps, but it doesn't last long because you add new tricks which make you slower again, and the process continues forever.
 

PetrusQuber

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Improvements usually come in jumps, and are often spread out with areas where your times are worse. Most of the time you learn anything new, your times get worse because your speed on the new tricks is very slow. Then eventually everything gets smooth and you get some PB jumps, but it doesn't last long because you add new tricks which make you slower again, and the process continues forever.
That makes a lot of sense to be honest
 

PetrusQuber

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The first two steps of the Petrus method take me about 2.4 and 3.0 seconds respectively. It's probably normal for the extension step to take a bit longer because you don't have 15 seconds of free planning time to use, but one way of working around this is to try to track the pieces needed for the square as you solve the initial 2×2×2 block so you don't waste 2+ seconds trying to find them or to decide which of three directions to extend the block.
Yes, thanks for the information. Since my first post, I think I've gotten better at the 2x2x3 and average around 6-10 seconds with it, but I ideally want it to be a solid 6. I think the cause is because I switched my technique of bulding the 2x2x1 and also practised holding my cube in a position so I could see more pieces at once (like switching from upside down cross to cross on bottom). Thanks for that tip though. Lots of my solves consist of looking around for pieces, as my lookahead is trash at the moment.
Soz for late reply, it didn't come up on my alert since I deleted my post.

New splits: 2x2x2 - 4-7 secs, 2x2x3 extens - 6-10 secs, EO is the same - 2-5 secs, Finishing F2L - 10 secs, LL - 10 secs.
 
Last edited:

PetrusQuber

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The first two steps of the Petrus method take me about 2.4 and 3.0 seconds respectively.
Ok then. I was slightly misled with the post on 'how to get faster using the petrus method' when it said the first block should be 4 seconds and the extension should be a total of six seconds. I thought that meant the extension was 2 secs.
 

PetrusQuber

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After doing EO, hold the cube so the solved block is at Left-Down, then only use R and U to solve F2L. If you use other moves, it will influence the edges.
Also, good to see more Petrus people :)
 

Mischiiii

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Nov 12, 2019
Messages
103
I’m cubing since July 2019 and im average around 45 sec. Im using CFOP with 3LLL. But I’m not training enough.
 

OreKehStrah

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May 24, 2019
Messages
225
I got sub-45 for all the methods I know(CFOP, Roux, ZZ, Petrus) in one day except for CFOP. However, part of it is that I learned them this year, which is my fourth year cubing, with occasional breaks so part of it is just practice and experience. Maybe try learning some other methods to introduce yourself to new ideas, and to help keep cubing fresh for you.
 

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