Yes I do. With some composers, I am certain (Bach). The constraints are formal enough. In organic chemistry you have a rulebook (fourty odd main synthetic reactions). You can go from A to B only following certain paths. There are formal in a sense that ther could be a completely unknown shortcut, but nobody would gamble on that in the middle of a 50-step synthesis. The same goes for composition of, say, contrapuntal music. You have considerable melodic freedom, but it has to molded in a certain form.