Let A≅k〈X〉/I be an associative algebra. A finite word over alphabet X is I-reducible if its image in a k-linear combination of length-lexicographically lesser words. An obstruction subword-minimal word. If the number obstructions then I has Gröbner basis, and problem for algebra decidable. cogrowth function length ≤n. We show that finitely presented either bounded or at least logarithmical. als...

In iterative schemes of identification and control one of the particular and important choices to make is the choice for a model uncertainty structure, capturing the uncertainty concerning the estimated plant model. This is typically done in some normbounded form, in order to guarantee robust stability and/or robust performance when redesigning the controller. Structures that are used in the re...