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I'm interested: Are there any sparks that can be created through glider synthesis? Ones that can be created with frontrakes, I mean. I'm asking this because that might make it possible to make a sort of "clean-up" system that protects the rakes.

Gamedziner wrote:I'm interested: Are there any sparks that can be created through glider synthesis? Ones that can be created with frontrakes, I mean. I'm asking this because that might make it possible to make a sort of "clean-up" system that protects the rakes.

Sure! If I'm understanding the question correctly, this kind of thing is done all the time, whenever a spaceship can't be found that supplies the required spark directly.

A good place to start might be the two-90-degree-glider "nothing" syntheses, in Golly's Patterns/Life/Syntheses/two-glider-collisions.rle. There are a lot of spark types that you won't find there -- phi sparks, for example -- but you can pick up a lot more options with three-glider collisions, or by building a small object with a two-glider collision or a puffer, and then sending a glider to annihilate it.

Mark Niemiec recently mentioned that syntheses of "edgy" non-stable junk, presumably including useful sparks, is one of the big missing pieces in his current database. A lot of spark syntheses are known by the glider-synthesis experts (i.e., not me), but you often have to run a search to find them, or inspect a lot of existing glider syntheses and pick out what you need. A big well-organized collection of edgy spark recipes would be really useful to have.