Another old question i had, is answered by the new list:
eleven wrote:DBS is equivalent to a combination of D and BS (equivalence in the sense, that if a puzzle has DBS symmetry, it also has both D and BS symmetry and vice versa). I dont have a proof for the "vice versa" part.
There cant be a proof for the other direction, because there is a group, which has D (or DM, class 37) and BS (class 22, now called JD) symmetry, but not DBS (class 43, which we called DM+JD). So the naming DM+JD is all but perfect.
The reason is the same i mentioned above. If a grid has the 2 symmetries and there is an equivalent grid, where both are in normalized form, it also has the symmetry with a number 6-cycle. If there is no equivalent grid, where both are in normalized form, there is no other symmetry forced.
Here are examples for the combinations of Sticks and Jumping-Row symmetries:
Both in normalized form:
- Code: Select all
+-------+-------+-------+
| 1 9 6 | 2 7 4 | 3 8 5 |
| 2 7 5 | 3 8 6 | 1 9 4 |
| 3 8 4 | 1 9 5 | 2 7 6 |
+-------+-------+-------+
| 5 1 8 | 6 2 9 | 4 3 7 |
| 6 3 9 | 4 1 7 | 5 2 8 |
| 4 2 7 | 5 3 8 | 6 1 9 |
+-------+-------+-------+
| 9 6 1 | 7 4 2 | 8 5 3 |
| 8 4 2 | 9 5 3 | 7 6 1 |
| 7 5 3 | 8 6 1 | 9 4 2 |
+-------+-------+-------+
Sticks (1)(2)(3)(47)(58)(69)
JR (123)(456)(789)
Sticks-JR (132)(495768)
Cant be both in normalized form:
- Code: Select all
after DM, c56
+-------+-------+-------+ +-------+-------+-------+
| 6 2 8 | 1 9 4 | 5 7 3 | | 6 1 3 | 9 4 7 | 8 2 5 |
| 1 9 4 | 3 7 5 | 6 2 8 | | 2 9 7 | 1 8 5 | 4 6 3 |
| 3 7 5 | 6 2 8 | 1 9 4 | | 8 4 5 | 6 2 3 | 9 1 7 |
+-------+-------+-------+ +-------+-------+-------+
| 9 1 6 | 4 8 2 | 3 5 7 | | 1 3 6 | 4 7 9 | 2 5 8 |
| 7 5 3 | 9 1 6 | 4 8 2 | | 9 7 2 | 8 5 1 | 6 3 4 |
| 4 8 2 | 7 5 3 | 9 1 6 | | 4 5 8 | 2 3 6 | 1 7 9 |
+-------+-------+-------+ +-------+-------+-------+
| 8 4 9 | 2 6 1 | 7 3 5 | | 5 6 1 | 3 9 4 | 7 8 2 |
| 2 6 1 | 5 3 7 | 8 4 9 | | 7 2 9 | 5 1 8 | 3 4 6 |
| 5 3 7 | 8 4 9 | 2 6 1 | | 3 8 4 | 7 6 2 | 5 9 1 |
+-------+-------+-------+ +-------+-------+-------+
Sticks (1)(24)(37)(5)(69)(8) JR (142)(375)(698)
Red Ed, please could you explain, what the class size and the "number of grids fixed up to relabelling" mean (how are they calculated). Is there any relation between those numbers and the number of non-equivalent (e-d/essentially different) grids, that have this symmetry ? I still would be interested in this number for each symmetry.
If i understood you right with giving nicer symmetry descriptions - the class numbers are ok for me as they are (clearer than our names). What i would like to have is, what udosuk did for the 26 classes: Give an example grid, where the symmetry is in "normalized" form, i.e. easy to spot. As we saw (first for the MC grid), for some symmetries this would need more than one grid.