Elf Help: Composing Options |
Six composing options are provided by Elf to help you speed up slow searches, or expand the results for quick ones. Generally you turn an option on for faster results, and off for a wider search; the exception is the Allow Bobs option which works the other way around.
| Tenors Together, Nice Part Ends, Optimum Balance, Maximum COM, | |
| Allow Bobs, LH Spliced Only |
Remember the options don't take effect until you press the Compose button!
If you check this option, Elf will only use method combinations which keep the tenors together at the leadends. For example, leadend 12547683 would be allowed, because bells 7 and 8 can be found in this position in a lead of the plain course of Plain Bob. However, 12548673 wouldn't be allowed, because the tenors are the wrong way around, and nor of course would something like 12348765.
This option can have a dramatic effect on the speed of composition, because depending on where the tenors are at the start of the lead, there are usually few combinations of methods which keep them together for the next lead, so the "branches" of the search tree are curtailed. This becomes less true if you have specified methods which have Plain Bob half-leads - for instance, Yorkshire, Superlative, Bristol and Ashtead will always keep the tenors together if spliced in any combination.
Note that if you have specified a composition with 7 or more parts, it is impossible to keep the tenors together in every part. Elf therefore only tries to keep them together in one part - in other parts a different coursing pair of bells will be kept unaffected. This type of construction is seen in compositions such as Norman Smith's 23-spliced.
Warning - some methods may be impossible to splice into the composition without splitting the tenors. London is an example - it cannot be spliced with any other method from the Standard 8 without splitting the tenors. If you have ticked the Tenors Together option, no compositions will be found at all.
Some searches of half-lead spliced produce billions of compositions, and much of the search time can therefore be spent in the relatively slow process of proving and counting up music. Anything we can do to reduce the number of compositions Elf has to check will help speed up the search. Of course, the vast majority of the compositions will be musically inferior, and often this is because the part end is unfavourable. For instance, when searching for 6-parts, a part end such as 13426578 is likely to produce more music than say 16254378. By ticking the "Nice part ends" checkbox, you can discard compositions which don't have desirable part ends. You're still likely to find the most musical compositions, but the search speed will be dramatically increased.
What counts as a nice part end?
| 2 parts | xxx5678, xxx6578, xxx8765, xxx5768, xxx7856 | |||
| 3 parts | 3425678, 4235678 | |||
| 4 parts | 3524678, 4253678, 2346875, 2347586 | |||
| 5 parts | 3526478, 5634278, 6452378, 4263578 | |||
| 6 parts | xxx5678, xxx6578, xxx8765, xxx5768, xxx7856 | |||
| 7 parts | Plain Bob leadends; cyclic partends (e.g. 3456782 etc) | |||
| 10 parts | 3257486, 3278564, 3286745, 3264857 | |||
| 12 parts | 234 and 5678 rotating; or 2345 and 678. |
Note that this option will have no effect on one-part searches! If you select "Tenors Together" you can further restrict the range of part-ends for the 2, 4 and 6-part search, and for 7, 10 and 12-parts, ensure at least one coursing pair is unaffected in every part.
By ticking the "Optimum method balance" box you can force Elf to ignore compositions that don't have the methods evenly distributed between the first and second halves of the leads. If you're searching for 7-part n-spliced touches with n leads per part, this will guarantee all results are ATW; if not, it will still ensure the best possible method balance, for instance making sure every method is represented in both the first and second lead halves.
This option allows Elf to prune huge brances of the search tree, because there are relatively few possible combinations of methods that are well-balanced as described above. You'll also find that it makes the initial time estimate more accurate, because the "heuristic" balance pruning algorithm is turned off. However, unless you definitely require ATW, you may find that many otherwise desirable compositions are missed.