Alexander's Star

Zaxef

Veteran
Joined
Jan 13, 2009
Messages
477
Location
Cambridge, Ontario, Canada
WCA ID
2009MATH02
So my girlfriend was out going to garage sales and she found me an Alexander's Star :)
25 cents!!

Anyway, I've solved the entire thing except for two pieces that need to be swapped on the top "layer" (The star made up 5 of pieces on the top is what I consider the last layer)
I'm wondering if that's because there can be parity and I need an algorithm for it or I just didn't do the last layer properly?

I tried to do it all without help and on the last layer I figured that if the edge can be swapped CW/CWW without being flipped then it's correctly oriented and all that "orienting" really does is flip the edge.. does that make sense?

And these last two edges are correctly oriented (I think... more details right below), they just need to be switched and the whole LL will be done.

The edges are oriented like this..

....1
.2.....5
..3..4

1: Red (left) Green (right)
2: Blue (front) yellow (back)
3: blue (left/back) orange (right/front)
4: red (left/front) yellow (right/back)
5: green (back) orange (front)

So that means that 3 and 5 are correct in relation to eachother, meaning that 2 needs to be where 1 is in order to match up with the blue on 3.
and putting 1 where 2 is would match up the red on 4.
If this is confusing I apologize.. I'm trying to be as clear as possible :fp
Looking at the puzzle like this it's 1 and 3 that need to swap.. well it could be any position but they're adjacent is the point
If you do give me an algorithm please remember to include where the two edges have to be on the puzzle, thanks!
Edit 2: I found a video on youtube that explained parity, so I was doing it right I just didn't know about the parity :)

I guess all I have to ask now is are they all 6 colored?
 
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I too have been having this problem lol

It is in fact a parity issue. I try to solve this puzzle just like I solve the edges on the bottom layer of the megaminx and it works great...except the megaminx does not get parity issues since it has 12 colors. However a 6 colored megaminx or an alexander's star does get parity issues.

The easiest (and it is very simple) way I have found of fixing this problem is to switch two identical pieces.

I do this by looking to see what color the bottom layer is. Then I replace one of the pieces from that bottom layer with one of the pieces from the top layer. This won't completely ruin all of the work you have done and with a little intuition I can quickly fix the parity. As for an actual algorithm...I don't know. I'll stay posted to see if anyone else has one, but for me, simply swapping two identical pieces works great.
 
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I got an algorithm off of youtube..

Switch two adjacent:
U2' D2 R2' U' R2 U2' D2'

Two opposite:
U2' D2 R2' U2' R2 U' D2'

Pretty easy to remember.. just switch the bolded moves in each alg to get the other
 
Hey, this algorithm works great. Thanks. Just one thing to be sure of when utilizing it is that the two edges to switch must be on the u face

thanks a million for the algorithm
 
I got an Alexander Star when they first came out, solved it to the parity state in a few hours and had no idea how to fix it so it sat for about 20 years in that state...I could of used the help of a youtube back then.
 
nobody_cares.jpg
 
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