"Category O" typically refers to a classification used within specific contexts, but without more context, it can be difficult to pinpoint exactly what you're asking about. Here are a few possibilities: 1. **Vehicle Emissions**: In the context of vehicle regulations, particularly in the EU, "Category O" may refer to vehicles that are categorized based on their emissions and environmental impact.
Articles by others on the same topic
For a finite-dimensional complex semisimple Lie algebra with a fixed triangular decomposition of a Lie algebra, category consists of finitely generated universal enveloping algebra modules that are direct sums of Cartan weight spaces and are locally finite under the positive nilpotent subalgebra. Their weight spaces are finite-dimensional and their weights lie in a finite union of downward positive-root cones. Verma modules, finite-dimensional modules, submodules and quotients belong to this category. Closure under submodules uses the noetherian property of the enveloping algebra, obtained from the Poincaré-Birkhoff-Witt theorem. The category condition does not require the module to be finite-dimensional.