# Let's talk about Petrus



## StachuK1992 (Mar 19, 2015)

Several years ago, I popularized the term "The Big Four," in reference to what I, at the time, thought were the four most powerful speedcubing methods.
http://stachu.cubing.net/rants/methodrantings.html


Petrus was always 4th place in my head, and I considered it inferior to the other methods.


Why?


I'm personally not sure.
Maybe it's due to empirical evidence as I haven't seen anyone 'fast' do petrus in a while.
Maybe the blocks take just a bit more brain-power than Roux's.
Maybe it's the awkward rotations between the 2x2x2, 2x2x3, and EO that I always seem to do.


For me, ZZ's the obvious choice for OH, and CFOP, ZZ, and Roux all seem to be equals in my head for 2H.


Thoughts? Why do I discriminate against Petrus?


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## Smiles (Mar 19, 2015)

I do the same thing. petrus is too intuitive and until last layer there's nothing that is done to speed it up other than move reduction. there are no finger tricks or useful move restrictions like roux and zz.

edit: the faster cubes we have the worse petrus becomes in relation to the big 3

oh and the eo step is way too hard.


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## waffle=ijm (Mar 19, 2015)

EO step is lame. Like you do it after blocks which then limits you so much. With ZZ, you have an open cube to work with so there's more efficiency in terms of move count. Petrus on the other hand has EO as it's own little step. Why don't we incorporate EO while building blocks or while finishing F2L? If Petrus was ever to be rewritten then I'd like EO to be fused with other steps rather than it being a step by itself, because as of right now EO takes a lot of moves for Petrus (well to me at least)


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## AlphaSheep (Mar 19, 2015)

Petrus isn't used as much for speedsolving, but it plays a big role in FMC.


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## cmhardw (Mar 21, 2015)

AlphaSheep said:


> Petrus isn't used as much for speedsolving, but it plays a big role in FMC.



Agreed, I think Petrus is a mainstay in fewest moves.


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## Dene (Mar 21, 2015)

Lol doesn't look like anyone wants to talk about Petrus. Too outdated.


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## Ranzha (Mar 21, 2015)

As someone whose cubing style is heavily influenced by Petrus blockbuilding, the times I get when I focus on a pure CFOP style tend to be faster.


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## DeeDubb (Mar 21, 2015)

I've been dabbling in CFOP, but I think on about 50% of my solves, I try to start with a 2x2x2 (X-Cross) which comes from being able to build blocks. I'm not sure if this helps me that much though.


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## Noahaha (Mar 21, 2015)

Ranzha said:


> As someone whose cubing style is heavily influenced by Petrus blockbuilding, the times I get when I focus on a pure CFOP style tend to be faster.



Same boat. Since I spent so long on Petrus, solving a 2x2x2 block comes most naturally to me. Unfortunately 4 times out of 5 it's better just to go for the cross.


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## mDiPalma (Mar 21, 2015)

My avg1000 with Petrus is 13.5. I'm not good at it, but it's the most fun method for me.

in my opinion, there are 3 reasons why the Petrus method *appears* slower than other methods. 

1) there's too much freedom (too many distinct things to look for at any given moment). there are too many decisions to consciously make in a speedsolve. it's impossible to weigh pros and cons of each possibility so quickly.

2) solves are "framed" in CFOP/ZZ/Roux solution styles, depending on the user. too many "Petrus" solves are just 3 cross pieces and 2 F2L pairs.

3) people are too lazy to inspect for more than 3 seconds. i often just find a good 2x2x2 or 2x2x1 and call it quits after a few moments of inspection.



how these problems could be solved:



Spoiler



1a) always decide ahead of time which 3x2x2 to expand to. Because my ZZ orientation involves blue/green on F and white/yellow on D, I can easily force myself into a particular expansion, but it may not be the most efficient/ergonomic.

1b) plan out the entire 3x2x2 in inspection

2) don't use dumb CFOP pairs. don't do EO ahead of schedule. Don't do 3x2x1->3x2x2. Do whatever is most efficient/ergonomic.

3) inspect for 15 seconds. or at least track where your block pieces will end up.




tl; dr - i think the best Petrus averages will come from a efficient, organized approach to blockbuilding, with a patient inspection phase


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## pdilla (Mar 21, 2015)

Lack of finger tricks and, as you say, awkward cube rotations which seem to lead to tougher look ahead are the biggest problems that I can see.


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## ion (Mar 23, 2015)

Lolz. Obviously, you have not studied the method seriously.
EO the hardest step ? No fingertricks ? Lolz lolz lolz


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## Smiles (Mar 23, 2015)

ion said:


> Lolz. Obviously, you have not studied the method seriously.
> EO the hardest step ? No fingertricks ? Lolz lolz lolz



lolz argument = convincing.
me = new outlook on life.


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## qqwref (Mar 23, 2015)

I think Roux and CFOP are really the big two. ZZ is pretty good, but I feel like at the same skill level and number of LL algs CFOP will end up faster. Petrus can be okay too, but the ergonomic point is definitely true - it does seem to require more thought than CFOP, and planning out a whole 2x2x3 block at once is not easy. The 2gen step is really not much of an advantage over just building pairs CFOP style (rotations and F moves are quite fast nowadays, thanks to improved hardware and fingertricks) and blockbuilding and EO do slow things down.

Remember, the list of methods that have seen a sub-10 avg12 is pretty short, and there is still a gigantic difference between that and sub-7. Petrus is reasonably popular and well-known, but I don't anticipate anyone becoming world-class with it as their main method. You might as well use Tripod (ben's had some really fast singles), or Heise, or my Columns thing, or Tao Yu's CFOP/Roux hybrid.


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## Smiles (Mar 23, 2015)

qqwref said:


> I think Roux and CFOP are really the big two. ZZ is pretty good, but I feel like at the same skill level and number of LL algs CFOP will end up faster. Petrus can be okay too, but the ergonomic point is definitely true - it does seem to require more thought than CFOP, and planning out a whole 2x2x3 block at once is not easy. The 2gen step is really not much of an advantage over just building pairs CFOP style (rotations and F moves are quite fast nowadays, thanks to improved hardware and fingertricks) and blockbuilding and EO do slow things down.
> 
> Remember, the list of methods that have seen a sub-10 avg12 is pretty short, and there is still a gigantic difference between that and sub-7. Petrus is reasonably popular and well-known, but I don't anticipate anyone becoming world-class with it as their main method. You might as well use Tripod (ben's had some really fast singles), or Heise, or my Columns thing, or Tao Yu's CFOP/Roux hybrid.



I feel like zz has potential because its designed for a speedy f2l, and the LS LL options are huge. someone will find a combination that works best, if only more people used the method.


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## GuRoux (Mar 23, 2015)

Smiles said:


> I feel like zz has potential because its designed for a speedy f2l, and the LS LL options are huge. someone will find a combination that works best, if only more people used the method.



i agree, zz zbll seems very promising.


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## mDiPalma (Mar 23, 2015)

what's the fastest official petrus average in competition?


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## Smiles (Mar 23, 2015)

maybe COLL + EPLL but take out all the mediocre COLL algs and replace them with kirjava's 1-look 2-alg set instead of ZBLL for easier recall and no need for practicing the algs.

oh and wv and sv whenever convenient of course.


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## stoic (Mar 23, 2015)

There was a similar sorta thread a few years back which y'all might find relevant.

Is Petrus a dead method?


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## ion (Mar 23, 2015)

You make the 222 in DBL. Then you expand to 223 in DBR (<R,U,F> fingertricks). Then you orient the edges (<R,U,F> fingertricks). Then you do ONE rotation (y'). Then you finish the F2L (<R,U> fingertricks). Then you do the LL (in your favourite way).

Weird rotations ? Bad fingertricks ? I don't understand why you say that. There is often only one rotation and blockbuilding is RUF (then RU).

Also, look-ahead. Once you made the 222, you can see ALL the unsolved cubies. All the hidden cubies are the solved ones.
And block-building don't require a lot of thought when you are used to it.

I'm not saying Petrus is the best method. I even think CFOP and Roux are slighty better. But Petrus is underrated, and is as good as ZZ in my opinion. ZZ has his advantages, but Petrus too (we look at only one side of the cube, we utilize only one hand...)
I can post speedsolves reconstructions if you are interested in.

(Also, sorry for my bad english.)


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## mDiPalma (Mar 23, 2015)

ion said:


> You make the 222 in DBL. Then you expand to 223 in DBR (<R,U,F> fingertricks). Then you orient the edges (<R,U,F> fingertricks). Then you do ONE rotation (y'). Then you finish the F2L (<R,U> fingertricks). Then you do the LL (in your favourite way).
> 
> Weird rotations ? Bad fingertricks ? I don't understand why you say that. There is often only one rotation and blockbuilding is RUF (then RU).



Yeah, that's exactly how I do it too. The disadvantages with Petrus are certainly NOT lookahead and rotations/ergonomics.

Please do post speedsolving reconstructions/videos!


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## GuRoux (Mar 23, 2015)

i think disadvantage of petrus is too much freedom and a high stress on efficiency. This leads to bad lookahead and rotations. i think if you formalize the block building depending on what you see in inspection, it will be much more manageable, and still retain good movecount and few rotations.


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## ion (Mar 23, 2015)

GuRoux said:


> i think disadvantage of petrus is too much freedom and a high stress on efficiency. This leads to bad lookahead and rotations. i think if you formalize the block building depending on what you see in inspection, it will be much more manageable, and still retain good movecount and few rotations.



Well, a lot of Petrus users think they must have a very low movecount, just because they use Petrus. It's a wrong approach. In speedsolving, movecount is not THAT important — we have to focus on ergonomy. Like I said, we can solve the cube with very few rotations and very good fingertricks, if we consent to do ~55/60 moves.

Unfortunely I have not the hardware to record me, but I will post some reconstructions later.


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## GuRoux (Mar 23, 2015)

ion said:


> Well, a lot of Petrus users think they must have a very low movecount, just because they use Petrus. It's a wrong approach. In speedsolving, movecount is not THAT important — we have to focus on ergonomy. Like I said, we can solve the cube with very few rotations and very good fingertricks, if we consent to do ~55/60 moves.
> 
> Unfortunely I have not the hardware to record me, but I will post some reconstructions later.



i can sub 55 moves in a slow solve pretty consistently just with 1x2x3 ->2x2x3, so someone better at petrus could probably do around 50 in a speedsolve and have little rotations, easy fingertricks, and good movecount.


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## porkynator (Mar 23, 2015)

I think I average about 12 with Petrus, yesterday I got a sub-8 single (I'm not sure if it is the first I get with Petrus); at the moment it's my second fastest method (I average 11 with ZZ).
I agree that being forced to solve EO 2 pieces at a time with 3 moves conjugates isn't nice, but it can be pretty fluent with good look ahead.
My approach is: start with any 2x2x2 block, then expand it in order to have W/Y on D and O/R in F (my usual ZZ orientation); it's easier for me to recognise EO this way, but I can also solve with B/G on F.
My thoughts: maybe Petrus is a bit underrated at the moment; I don't know if it has the right to be part of the "big 4" due to lack of evidence, but I see the potential for (at least) sub-10 global average with it (not by me).
A side note: I think it is really nice as an intermediate method, and I have succesfully taught it to a beginner in just a couple of "lessons". I wish I had started with Petrus and then moved on to something else (or even stuck to it, why not).


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## ion (Mar 23, 2015)

I agree, it's a very pedagogical method. You can learn a lot of things about how the cube works, and it's quite natural (as Lars say, the first layer is not natural because you can't do anything without breaking it). I think it's not a very good idea to teach a layer-by-layer method to a newbie, because it's just... well, stupid.


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## TDM (Mar 23, 2015)

ion said:


> You make the 222 in DBL. Then you expand to 223 in DBR (<R,U,F> fingertricks). Then you orient the edges (<R,U,F> fingertricks). Then you do ONE rotation (y'). Then you finish the F2L (<R,U> fingertricks). Then you do the LL (in your favourite way).
> 
> Weird rotations ? Bad fingertricks ? I don't understand why you say that. There is often only one rotation and blockbuilding is RUF (then RU).
> 
> ...


RUF =/= good fingertricks


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## obelisk477 (Mar 23, 2015)

TDM said:


> RUF =/= good fingertricks



Well which 3-gen set do you prefer then? I personally find RUL awkward. Maybe RUD, but until recently, not too many algs have been generated using it.


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## TDM (Mar 23, 2015)

obelisk477 said:


> Well which 3-gen set do you prefer then? I personally find RUL awkward. Maybe RUD, but until recently, not too many algs have been generated using it.


I prefer RUF, but the point I'm trying to make is that just because it's RUF, it doesn't necessarily mean the fingertricks are good.


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## ion (Mar 23, 2015)

You're right, but they are.


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## TDM (Mar 23, 2015)

ion said:


> You're right, but they are.


Do you honestly think they're as good as Roux, CFOP or ZZ?


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## Smiles (Mar 23, 2015)

ion said:


> You make the 222 in DBL. Then you expand to 223 in DBR (<R,U,F> fingertricks). Then you orient the edges (<R,U,F> fingertricks). Then you do ONE rotation (y'). Then you finish the F2L (<R,U> fingertricks). Then you do the LL (in your favourite way).
> 
> Weird rotations ? Bad fingertricks ? I don't understand why you say that. There is often only one rotation and blockbuilding is RUF (then RU).
> 
> ...



first of all, at least in my opinion, weird rotations and bad look ahead are not Petrus problems so i will not address them.

Relatively difficult block building:
- because many pieces aren't oriented. In Roux you use M/M' to orient, in CFOP you use y/y', and in ZZ they're all done. F moves are slow.
- because you have the freedom to expand 3 ways (more thinking). if you limit yourself to 1 (less thinking) then you might as well do an xcross.

Annoying to fix bad edges:
- because there are some bad cases and sometimes it's just not worth it.
- because you have to recognize mid-solve, which may require a pause if there are a lot (ZZ uses inspection for this which is better)
- because 3 moves = 2 edges

Bad finger tricks:
- relative to CFOP (F2L algs) / ZZ <R,U,L> / Roux <R,r,U,M> or moo.
- RUF is not better than RUL because RUL means "2gen on the left side and then 2gen on the right side". RUL is *not* the same as an RUL V perm or RUL N perm, because those are rapidly alternating R/L and thats why they suck. If you have to do a lot of F moves at once, it's faster to just rotate. that's the premise of CFOP, at least.

F turns are not good. the other methods try and avoid F turns. they're fine for specific algorithms where they integrate nicely (like J perm).

But there are good things about Petrus:
- low move count
- EO done at LS/LL (slight advantage)
- 2-gen for last block (not sure if this is advantageous because the EO step is required for this)

I'm not saying petrus sucks. it doesn't. it's big 4. but there are many reasons why it's not as good as the big 3.



ion said:


> There is often only one rotation



ZZ = no rotations
Roux = no rotations
CFOP = usually more rotations, but no matter how many bad edges, i can force there to only be 1 rotation. if you let me use F turns a lot (like petrus), i can guarantee you more than 50% of my speedsolves will have no rotations. but F turns are slow, so i rotate instead.

Petrus = build a block on DBL without ever using a B move? i sense that there are often 2 cube rotations.

out of curiosity, is petrus your main method?


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## ion (Mar 23, 2015)

> difficult block building = relative to ZZ because your pieces aren't oriented yet.



Slighty more difficult, but still okay. Rouxers use M to deal with bad edges, Petrus use F. Of course M is more comfortable, but not really _easier_. Just a matter of experience. In most cases it's the same strategy.



> difficult block building = because you have the freedom to expand 3 ways (more thinking). if you limit yourself to 1 (less thinking) then you might as well do an xcross.



I tend to limit to one, less thinking and less rotations. XCross is cool but I still like the 223, it's very ergonomic and you have a good view of the cube.



> hard to fix bad edges = because there are some bad cases and sometimes it's just not worth it.
> hard to fix bad edges = because you have to recognize mid-solve, which may require a pause if there are a lot (ZZ uses inspection for this which is better)



Erik Johnson used to solve bad edges in one second. Recognition and moves are very fast most of the time. Bad cases happen but actually you can say that for every step in every method.



> bad finger tricks = relative to CFOP (F2L algs) / ZZ <R,U,L> / Roux <R,r,U,M> or moo.



I really don't see why they're bad relative to CFOP or ZZ. It's RU most time, with some F (not a lot though). Mixing two hands have disadvantages too.




> F turns are not really good btw. all the other methods avoid F turns. they're fine for specific algorithms where they integrate nicely (like J perm).



F turns integrate nicely in EO. Not so much in 223 though, I admit it.



> I'm not saying petrus sucks. it doesn't. it's big 4. but there are many reasons why it's not as good as the big 3.



Maybe you're right. I'm not sure. It's impossible to be sure about that. The gap is probably very short (at least relative to ZZ).



> if you let me use F turns a lot (like petrus), i can guarantee you more than 50% of my speedsolves will have no rotations. but F turns are slow, so i rotate instead.



You rotate to do F insertions (like F'UF) or similar things. You have not things like that in Petrus. F turns are typically alone, and most of the time they combine well with R turns.



> Petrus = build a block on DBL without ever using a B move? i sense that there are often 2 cube rotations.



I didn't consider the first step, which is very situation-dependant (in every method).



> out of curiosity, is petrus your main method?



Yes it is.



> I'm not saying petrus sucks.



I know. Actually I find this discussion interesting.
Also, I don't intend to be stubborn. I just feel like there is a lot of misconceptions and clichés about Petrus method. I'm very aware that it's not a perfect method (not straightforward enough, I guess).


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## TDM (Mar 23, 2015)

ion said:


> I tend to limit to one, less thinking and less rotations.


But more moves, meaning you're not taking advantage of Petrus' efficiency, which is, in my opinions, its most important advantage over other methods.


> XCross is cool but I still like the 223, *it's very ergonomic*


I'm still not convinced it's anywhere close to building an EO223 in ZZ, F2B in Roux or CFOP F2L.


> Erik Johnson used to solve bad edges in one second.


Really? Do you have any proof?


> Recognition and moves are very fast most of the time. Bad cases happen but actually you can say that for every step in every method.


I wouldn't have thought recognition would be as easy as with the other three methods. Again, I don't think the moves are faster. ZZ/Roux/CFOP all have very easy to fingertrick steps for 90% of the solve, not 50%. And actually, the bad cases with Roux and CFOP aren't that bad at all. I think this is one of the limitations of ZZ though.


> I really don't see why they're bad relative to CFOP or ZZ. It's RU most time, with some F (not a lot though). Mixing two hands have disadvantages too.


There are a lot more F moves in Petrus than CFOP. With ZZ they're all done in the start, planned in inspection and done quickly - definitely faster than Petrus. Petrus has a lot more F moves. Mixing two hands isn't bad with CFOP, since usually the regrip isn't noticable as you rotate - but again, this is one of the problems with ZZ.


> Maybe you're right. I'm not sure. It's impossible to be sure about that. The gap is probably very short (at least relative to ZZ).


ZZ isn't that far behind the other methods, since although it has the disadvantages compared to CFOP I said above, it has other advantages over CFOP. The gap between Petrus and the other methods is much bigger.


> You rotate to do F insertions (like F'UF) or similar things. You have not things like that in Petrus. *F turns are typically alone*, and most of the time they combine well with R turns.


What do you mean by this?


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## Smiles (Mar 23, 2015)

i think it means that instead of using F for CFOP-style inserts (pairs of F moves like the example), they occur less frequently and not in pairs.
i'm not sure if this is actually true though.


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## Kirjava (Mar 26, 2015)

I'm of the conviction that it lends itself to high movecounts and more difficult recognition when used as a speed method - and the EO step really isn't helping.

Do we have a decent amount of recons for a 'fast' petrus user?


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