Comments/Ratings for a Single Item

"A switch is an overlapping pair of spaces that in some ways operate together as a single space."

From my point of view it looks different. The square a4 of a switch is an independent square and is completely identical to the square a4 in normal chess. 4 (A4) is a composite square consisting of a half and triangle part of a4 and the new triangle due to board geometry. The new square 4 (A4) gets the same play options as all squares of the game board - 4 (A4) is considered equal.

This means that the squares a4/4 (A4) must first be seen independently. These independent fields get an additional function when they work together and act as a switch, as described.

I didn't say anything different. We're in agreement that the spaces composing a switch are separate from each other. But since they cannot be simultaneously occupied, and occupation of one space blocks movement through the other, and they share a common edge and a common corner, they also function in some ways like the same space.

It is possible to agree on the sides from which the switch should be accessible. We have clarified access from below and from the side, access from above is also not a problem and is already part of my proposal. The only question is whether it is access to the switch as a unit or to the individual square of a switch. According to my intention, the second applies.

Agreed. Use of the switch as a switch is possible only from below. That is due to the nature of how it works. If a piece moves to a switch through a diagonal move or a Knight move, it will have to stop on the switch, which will prevent it from using the switch to alter the direction of its movement. The same is true if a Rook or Queen moves to a switch from the side. It will have to stop there, which will prevent its use as a switch. And if a Rook or Queen moves to a switch from above, it will have only one path through the switch. So, it won't be utilizing the switch as a switch. This shows that access to the spaces composing a switch is a completely different matter than using it as a switch.

"Allow pieces access to the spaces of a switch from any direction, and when a piece moves to a switch, allow capture of any piece on the switch even if the capturing piece moves to the other space. For example, if a bishop is on A4, and a Rook moves to a4, consider the Bishop on A4 to be captured."

As described, access to the switch from all sides is not a problem. It is possible to agree on the proposal, but it does not fit my intention. However, if the game becomes more playable and programmable - so what.

What I'm proposing fits with the rule that both spaces of a switch cannot be occupied at the same time and the rule that occupancy of either space blocks vertical movement through the switch even when that movement would technically be going through the other space in the switch.

To the Knight: I can't allow anything here, but I can say what my point of view is. If we stick to the fact that the squares of a switch should be seen separately, then knight moves ending on the same line are not possible. However, as the game becomes more playable and programmable, compromises should be possible.

We could just say that because of the way that switches affect the geometry of the board, some spaces may be reached by either a vertical move or a Knight move. This would also correct the injustice done to the Knight of making the weakest piece even weaker around a switch while it gives all other pieces greater mobility.

"One last rule change I would suggest is to let Rooks, Queens, and Kings use their ability to move horizontally to switch between the spaces constituting the switch. This would basically involve lifting one more restriction on movement to the spaces making up a switch. "

I have problems with that. I have emphasized that the squares of a switch represent independent squares. This would rather mean that moves between the squares of a switch are possible.

Precisely.

The independence of the squares on the one hand and the functionality of a switch on the other compete with each other. Regarding the direct change between the squares of a switch, I tend towards the superordinate function, so a direct change should not be possible.

Allowing a piece that can move horizontally to move from one space to the other in a switch as a normal move does not affect the functioning of the switch. While the piece is on either space, other pieces can't pass through the switch, and once the piece leaves the switch, pieces will be able to pass through it again.

You're right. I have disregarded the change between the 4th and 5th rank. I fell into my own trap :).

You can agree on almost everything, certainly to make the game playable and programmable. Regardless of that, I can only say my point of view and describe my intentions.

"A switch is an overlapping pair of spaces that in some ways operate together as a single space."

From my point of view it looks different. The square a4 of a switch is an independent square and is completely identical to the square a4 in normal chess. 4 (A4) is a composite square consisting of a half and triangle part of a4 and the new triangle due to board geometry. The new square 4 (A4) gets the same play options as all squares of the game board - 4 (A4) is considered equal.

This means that the squares a4/4 (A4) must first be seen independently. These independent fields get an additional function when they work together and act as a switch, as described.

My intention is therefore not compatible with the proposal to merge fields 4/a4 (A4) as proposed by Jean-Louis.

It is possible to agree on the sides from which the switch should be accessible. We have clarified access from below and from the side, access from above is also not a problem and is already part of my proposal. The only question is whether it is access to the switch as a unit or to the individual square of a switch. According to my intention, the second applies.

"Allow pieces access to the spaces of a switch from any direction, and when a piece moves to a switch, allow capture of any piece on the switch even if the capturing piece moves to the other space. For example, if a bishop is on A4, and a Rook moves to a4, consider the Bishop on A4 to be captured."

As described, access to the switch from all sides is not a problem. It is possible to agree on the proposal, but it does not fit my intention. However, if the game becomes more playable and programmable - so what.

To the Knight: I can't allow anything here, but I can say what my point of view is. If we stick to the fact that the squares of a switch should be seen separately, then knight moves ending on the same line are not possible. However, as the game becomes more playable and programmable, compromises should be possible.

"One last rule change I would suggest is to let Rooks, Queens, and Kings use their ability to move horizontally to switch between the spaces constituting the switch. This would basically involve lifting one more restriction on movement to the spaces making up a switch. "

I have problems with that. I have emphasized that the squares of a switch represent independent squares. This would rather mean that moves between the squares of a switch are possible. The independence of the squares on the one hand and the functionality of a switch on the other compete with each other. Regarding the direct change between the squares of a switch, I tend towards the superordinate function, so a direct change should not be possible. At least that's my intention. But here, too, compromises determine reality.

Move 17: N a4-c3 doesn't seem legal, but N a4-c2 would be legal.

It looks legal to me. Why wouldn't this move be legal? Meanwhile, a4 and c2 are along a diagonal, and N a4-c2 would definitely be illegal.

Move 25: N f5-c4 doesn't seem legal in same way, but N f5-d4 would be legal again.

N f5-c4 is a perfectly legal Knight move, and I see no reason why it would be illegal. Meanwhile, f5 and d4 are diagonally adjacent, and N f5-d4 is clearly illegal.

When you're examining the moves, be sure to click on Record, paste the moves into the box, and click on View. This will let you view each position. I think you made some wrong judgements, because you got confused about how notation for this game works. Vertical movement shifts to an adjacent file as it goes between the 4th and 5th ranks. So, the space immediately above d4 is e4, for example.

I have started writing up a brief summary of the rules to appear underneath the board for Game Courier.

The moves B a4–c2; R a6–4 are legal moves, they are conform to the rules.

Move 17: N a4-c3 doesn't seem legal, but N a4-c2 would be legal.

Move 25: N f5-c4 doesn't seem legal in same way, but N f5-d4 would be legal again.

According to my definition, the switch can only be operated from 'below'. After that, the move N c5-A4 would not be possible.

A switch is an overlapping pair of spaces that in some ways operate together as a single space. By their very nature, they operate as a switch only from a given direction. From below, a piece is given two choices for how to continue its vertical movement. However, this property of a switch is not a property of the individual spaces whose overlap constitutes the switch. So, restrictions on movement to A4 have nothing to do with your definition of a switch. They are simply arbitrary restrictions on movement.

There are already other examples of A4 being reachable from above. For example, a Rook or Queen on a8 could move to A4, and a Bishop or Queen on e8 could move diagonally to A4. You have also agreed that it makes sense to let it be reachable from the side.

I'm now going to propose some rule changes. Since the switch can make a piece more powerful, this should be balanced by making a piece using a switch more vulnerable. Allow pieces access to the spaces of a switch from any direction, and when a piece moves to a switch, allow capture of any piece on the switch even if the capturing piece moves to the other space. For example, if a Bishop is on A4, and a Rook moves to a4, consider the Bishop on A4 to be captured.

Currently, the Knight is the only piece whose powers of movement are restricted in the vicinity of a switch. Correct this by allowing a Knight to move to any space that can be reached by a step in an orthogonal direction followed by a step in an outward diagonal direction, or by a step in a diagonal direction followed by a step in an outward orthogonal direction. This is the normal definition for how a Knight moves in Chess and other variants, and it would allow the Knight to also increase its capabilities in the vicinity of a switch.

One last rule change I would suggest is to let Rooks, Queens, and Kings use their ability to move horizontally to switch between the spaces constituting the switch. This would basically involve lifting one more restriction on movement to the spaces making up a switch.

It is probably appropriate to add that the switch can be operated not only from 'below' but also from the side.

Seeing as it can also be operated from ‘above’ too, if not already occupied (i.e. from my understanding, B a4–c2; R a6–4 is legal), I would agree that'd make sense.

17. N a4-c3 ---> N a4-c2

25. N f5-c4 ---> N f5-d4

?? Are those corrections? Aren't those diagonal moves, the way you've assigned file labels? of two and one steps respectively?

"That's interesting; given that a rook is allowed to move sideways from 4 onto b4 and beyond, that means that a rook on 4 can threaten a rook on b4 without being attacked back. Is this intentional?"

That doesn't seem logical indeed.

Assuming a rook is on 4 and an opponent's rook is on e4, my definition means that the rook on 4 can attack the rook on e4, but the reverse is not possible. That's inconsistent. It is probably appropriate to add that the switch can be operated not only from 'below' but also from the side. This would eliminate the inconsistency.

"En Bw" - sorry, won't happen again.

8. N c5-A4

According to my definition, the switch can only be operated from 'below'. After that, the move N c5-A4 would not be possible. N d5-a4 would be possible. However, in my reply to Bn Em I proposed an extension of my definition.

17. N a4-c3 ---> N a4-c2

18. N f5-c4 ---> N f5-d4

I'm done working on Chess66 for Game Courier today. The directions are looking good, but I still have to adapt the Pawns to work with switches, and I still have to prevent double occupancy of the switches. Since Firefox won't remember this after I shut down my computer, here are the moves I've been making to test things out. In the meantime, feel free to check it out, and apart from the issues I just mentioned I still need to work on, let me know if you find any illegal moves it permits or any legal moves it doesn't permit.

1. P c2-c4 
1... p f7-f5 
2. Q d1-A4 
2... q e8-H5 
3. Q A4-a7 
3... p f5-e4 
4. N b1-a3 
4... q H5-e5 
5. P c4-d5 
5... q e5-d4 
6. N a3-c5 
6... p e7-e6 
7. Q a7-a3 
7... b f8-e7 
8. N c5-A4 
8... b e7-g4 
9. P b2-b3 
9... b g4-H5 
10. P b3-b4 
10... q d4-b4 
11. Q a3-g3 
11... p g7-g5 
12. P d5-e6 
12... p g5-f4 
13. Q g3-h7 
13... r h8-h7 
14. N A4-d5 
14... b H5-g6 
15. N g1-h3 
15... n b8-c6 
16. N d5-a4 
16... b g6-h5 
17. N a4-c3 
17... q b4-c5 
18. P e2-e3 
18... b h5-h4 
19. P a2-a3 
19... q c5-h5 
20. N c3-a4 
20... q h5-h6 
21. N a4-c6 // - Check! -
21... p b7-c6 
22. N h3-f4 
22... q h6-e6 
23. N f4-h6 
23... q e6-d5 
24. N h6-f5 
24... n g8-h6 
25. N f5-c4 
25... b h4-e8 
26. P a3-a4

En Bw

I assume you mean me? That's one correct letter out of four, with two more misplaced ;)

The other one was turned upside-down but left in place. So, they're all there with some mix-ups. :)

A rook/queen on the rank 4 can only occupy square a4 and not square 4. This applies to the switch h5/5 vice versa.

That's interesting; given that a rook is allowed to move sideways from 4 onto b4 and beyond, that means that a rook on 4 can threaten a rook on b4 without being attacked back. Is this intentional?

The squares 4 and 5 do not have a uniform color. The squares are each composed of both colors.

Strictly speaking, the colours on the squares are a representational convention and bear no real influence on the game; ‘a bishop can change colour’ is equivalent to saying a bishop can reach the whole board, or in other words all squares are effectively the same colour. But that's a minor quibble

En Bw

I assume you mean me? That's one correct letter out of four, with two more misplaced ;)

I don't think that the moves to a5 and b5 are legal since they are on the same line.

That's one of the few things which changes depending on the knight‐move definition; the definition you've chosen would indeed exclude both destinations, as a queen can reach both of those squares; but the more usual definitions H.G. first brought up (either two othrogonal steps in one direction and one at right angles, or (my preferred expression) one orthogonal and one diagonally outwards — in either order (or not…?) and for some suitable definition of ‘outwards’) would probably allow both moves. Equally the question of whether N h4–g6 is legal, and probably other similar moves, is implicated there. There may be some way of defining the knight move to include only a subset of the moves in question, but that's unltimately for Gerd to decide if he wants to look for (or someone else to contribute if they come up w/ sth).

I don't think that the moves to a5 and b5 are legal since they are on the same line. Merging the squares 4 and a4 would not change that. On the contrary, the possibility of being able to detect movements on the same line or the same diagonal would be diluted.

I'm testing my code for Chess66 on Game Courier right now, and with a Knight on a3, I currently have its legal moves as a5, c5, c4, c2, and b1. Because 4 is right above it, it looks like b5 could be another legal move by going over 4 and a5 and turning right to b5. It could be argued that this is illegal because there is a single-direction path from a3 to b5. But if that rules that out, it might also rule out a5 as a legal move, because there is a single-direction path to it through 4.

Dear En Bw, thank you for your comment, which is absolutely correct.

I try to follow. So a Rook cannot go from a4 to 4. And I understood that if there is a piece on a4, it is not possible to have another piece on 4.

At the end I wonder if this game is simply playable. I wouldn't be able to explain it to anyone I'm afraid.

I'm pretty sure that it would be possible to build something interesting on Gernd's idea by melting the cells a4 & 4, as well as h5 & 5. Which was similar to HG's diagram.

Doing this

• only 1 piece allowed on a4/4 or on h5/5
• a Rook on a1 would threat up to b8 AND a8 (as wished by Gernd)
• a Rook on h4 would threat up to a4/4
• a Bishop on d1 would go up to a4/4
• a Bishop on a4/4 would either go to f8 (keeping the color) or to d8 (switching the color).
• a Knight on a4/4 could go to b6, c5, a6, c6, b3, a2, b2, c3 (interesting)
• Chess 66 would have 64 cells which is maybe the real problem.

"So, I gather that the following are all legal moves:

B d1-4, B 4-d1, B e8-5, B 5-e8"

That is absolutely correct.

"So, it looks like the diagonal from 4 to the first rank is a different color than 4, and the diagonal that goes from 5 to the last rank is a different color than 5, and that is how the color changing is done."

By the way: The squares 4 and 5 do not have a uniform color. The squares are each composed of both colors. This is the only way to make a color change possible.

I had already answered that before, as follows:

A rook/queen on the rank 4 can only occupy square a4 and not square 4. This applies to the switch h5/5 vice versa.

Suppose I have a Rook on d4. Could it move to 4? Or could it only move as far as a4? Likewise, could a Rook on d5 move to 5, or could it only move as far as g5?

The move sequences given by Gerd in his comment are B d1–4; B 4–b5 and B d1–5; B 5–g6.

So, I gather that the following are all legal moves:

• B d1-4
• B 4-d1
• B e8-5
• B 5-e8

I think I misread an earlier answer. This actually describes one move on black spaces and the other move on white spaces:

If the bishop is on 4, then his path goes via b5, c6, d7 to e8. In the other direction it goes via b3, c2 to d1.

So, it looks like the diagonal from 4 to the first rank is a different color than 4, and the diagonal that goes from 5 to the last rank is a different color than 5, and that is how the color changing is done.

a series of moves in the generic rule-blind style of notation I used earlier

The move sequences given by Gerd in his comment are B d1–4; B 4–b5 and B d1–5; B 5–g6. He also notes that B d1–h5 is not legal, but B d1–a4 is.

How come the Bishop goes from 5 to g6?

The top corners and the top and left sides are shared between h5 and 5, but the bottom side and corners are different. So 5 behaves as h5 from above (and cannot be occupied at the same time as it), and so is diagonally adjacent to g6.

When the Bishop goes from 5 to g6, is it affected if another piece stands on h5?

5 and h5 cannot be occupied simultaneously, so this situation does not arise. But since both are diagonally adjacent (by the same corner) to g6, it would presumably be fine if they could.

Does that answer your question?

No, it does not. I specifically asked for a series of moves, and I didn't get that. What will answer my question is a series of moves in the generic rule-blind style of notation I used earlier. You do not have to write anything in English to answer this question.

The more it's explained, the less I understand. The "a bit difficult" seems soft in my case. Here,

"Bishop on d1 to the right: The move can go up to 5 (and not h5, this square cannot be occupied). The next move can be continued via g6, f7 etc"

How come the Bishop goes from 5 to g6?

You said h5 cannot be occupied (by this Bishop I presume).

When the Bishop goes from 5 to g6, is it affected if another piece stands on h5?

Let me emphasize again: A change between 4 on a4 or h5 and 5 is not possible.

Some examples.

Bischoff on d1 to the left:

Standing on a4 after the move, a color transfer is not possible. Standing on 4 after the move, then a color transfer is possible. Because from there you can continue in the next move via b5, c6 etc., a color change has taken place.

Bishop on d1 to the right:

The move can go up to 5 (and not h5, this square cannot be occupied). The next move can be continued via g6, f7 etc. There has also been a color change.

For the other half of the board everything is vice versa.

Does that answer your question?

By what series of moves can a Bishop change to spaces of the other color?

The separation of the squares 4/a4 and h5/5 in the switches applies to all game pieces, including pawns.

Maybe I can clarify again from my point of view, especially for the knight:

A choice between the squares 4/a4 and h5/5 only goes in one direction. If a piece starts from a1/a2/a3 or from d1, c2 and so on, then there is a choice between squares 4 and a4, whereby the positioning must be clearly on 4 or a4. This means that the choice in a switch is only possible from 'below'. A rook/queen on the rank 4 can only occupy square a4 and not square 4. This applies to the switch h5/5 vice versa.

To clarify with the knight: A knight on 5 can move as shown in figure 10. Knights on g7 or f6 can occupy 5 or h5 because they come from 'below'. A knight on e4 can only reach h5 and not 5. A knight on g3 can only reach 5 but not h5. And a knight on f4 can move to 5 but not to h5.

This means that the squares of a switch are always seen separately and not partially as a same space.

It might be a bit difficult, but I hope it's consistent.

Since a Bishop that moves to 4 could immediately switch to a4, is the reverse also true? Could a Bishop moving to a4 immediately switch to 4? More generally, is switching between these spaces available for any piece or only for Bishops?

I have begun to program Chess66 for Game Courier. So that 4 and 5 have separate file labels, I'm calling them A4 and H5 and distinguishing them from a5 and h5. I'm programming it with logical directions, which lets me define named directions as linked lists of nodes. The way directions are defined, the same direction cannot have two destinations from the same space. This means I've had to define additional directions to handle some lines of movement. However, the same direction can go from different spaces to the same destination.

One of the main difficulties I'm coming across is that sometimes it makes sense to treat A4 and a4 or H5 and h5 as separate spaces, and sometimes it makes sense to treat them as the same space. One idea would be to put an invisible dummy piece on the unoccupied space when the other one is occupied. That way, movement through a switch would be completely blocked.

At present, more work needs to be done to get the directions working properly.

a Knight on one of these spaces could not move as though it were on the other space. However, that looks like what the Knight is doing in your example

That much is clarified in the accompanying text. All three of e4, f6, and g7 can be reached by an orthogonal step (taking into account the rule about sideways moves from 5 going directly to g5) followed by a diagonal step.

This holds equally well whether we use the author's preferred definition for the knight move or either of the more common ones H.G. suggested

there are no bugs in the variant and the set of rules is consistent. Complicated, yes, but conclusive.

Afaict, the rules themselves are indeed consistent (and may well lead to an interesting game), but the explanation could be clearer, as shown by the fact that they seem to be unclear in some respect of another to most of the readers here.

Also I second H.G.'s request for clarification on the matter of knights moving through/over closed switches

I agree with your understanding Fergus. The best way to describe this geometry in a consistent manner for all pieces, remains to consider a4 and 4 (or h5 and 5) as a double cell. A piece on this double cell can be seen as being on both. Then, the diagram drawn by H.G. is fully correct.

I gather from the comments that my version is not easy to understand.

I don't know if it's that or if you just haven't explained it clearly.

But if I see it correctly, then there are no bugs in the variant and the set of rules is consistent.

With respect to the Bishop, you told me that it can occupy only 4 or a4 or only 5 or h5. I presume the same holds for other pieces. So, a Rook on one of these spaces would not command two files. Likewise, a Knight on one of these spaces could not move as though it were on the other space. However, that looks like what the Knight is doing in your example. It's on 5, and its ability to move to f4 or g3 makes sense in light of that. But its ability to move to e4, f6 and g7 would make sense only if it were on h5 instead of 5.

If I may summarize from my point of view:

I gather from the comments that my version is not easy to understand. But that's not a disadvantage a priori. It remains to be seen whether the possibility of checkmating the king with just one piece will play a role in chess. The same applies to the bishop, who can now change his color diagonal.

But if I see it correctly, then there are no bugs in the variant and the set of rules is consistent. Complicated, yes, but conclusive.

A somewhat simplified version of the same idea is this:

There is only a single, double-width cell a4 here, and there is no additional game state to distinguish between an occupant being in the right or left half of it. Moves (or move continuations) that leave a4 to 5th rank can choose whether they consider a5 or b5 the only square that connects to the upper edge of a4. So a4 has 2 'north' exits (to a5 and b5), two 'north-east' exits (to b5 and c5), and a single 'north-west' exit (to a5).

The difference with the rules that were given is that 'forward' moves even fork from a4, in addition to a1-a3.

How a Knight should move in the vicinity of the switch fields depends on which of the (normally equivalent) descriptions of Knight moves one adopts for the regular part of the board. The description "all two-step King moves that cannot be made by a Queen" is a rather unusual one; commonly one finds "one orthogonal King step followed by an outward diagonal one" (i.e. a non-lame Mao) or L-shaped "2 orthogonal steps plus a perpendicular one". Where the latter might also allow the move to start with the short leg. In my opinion the non-lame Mao description would be most intuitive here.

Something doesn't work with this diagram. Maybe it is because only 2 colors are used, and a third one, neutral, should be used. Or because the triangular/losange doesn't work fine and something else has to be imagined.

I see the comments. It needs a lot of imagination to visualise something else and tell our brain that what we see is not right. What I see is simply a 66-cell board, where c1-b2-a3-4 is a diagonal, as well as 4-b5-c6-d7-e8, both being dark.

And a8-a7-a6-a5-4 is a column simply ending in 4. Like h1-h2-h3-h4-5, ending in 5.

That board only shifts the column (a to b, b to c, etc.) at the middle line. It doesn't change the color of the diagonals at all.

I understand the idea behind, but I think it needs to be worked more.

Right. So there is no path 4-a3-b2-c1. Which is what I meant, and needed to be said, because in the representation I had drawn, it looked like there could be.

I am still looking for a somewhat more intuitive description. It looks like 4 and a4 are really the same cell, (double width in my drawing), which always borders b4. And that there is a sliding door that either closes off the connection with a5 or b5, which has to be set as soon as you enter 4/a4, and can then not be altered until you leave it. (Which could be on the same turn.) Entering from above forces you to set the door such that you could enter.

May I refer to an earlier answer, which I hope answers your question:

"Let's say a bishop is on a4/4."

Let me be specific: a bishop doesn't stand on a4/4; he stands either on 4 or a4. The player must clearly mark the location.

If the bishop is on 4, then his path goes via b5, c6, d7 to e8. In the other direction it goes via b3, c2 to d1.

If the bishop is on a4, then he can choose; he can go down to d1 as before. He can move upwards to a5 in a first move, to go via b6, c7 to d8 in a second move. The other option is to move to f8 via c5, d6, e7.

There are no other move-options.