Alex, Matteo, Igor, Lists, A one-dimensional structure is often an awkward approximation to some n-dimensional structure. For example, C. S. Peirce invented the one-dimensional notation for predicate calculus (which Peano modified by introducing letters drawn upside-down and backwards). But he later simplified and generalized the notation with graphs, which can be drawn in two dimensions. But they are even simpler in three or more dimensions, when they avoid issues about cross-overs. More recently, category theory has been generalized to "infinity categories". Infinity may sound complex, but it is actually simpler because it removes many details that depend on some specific number N. The proofs are often simpler when many of the details can be ignored. For an introduction to infinity mathematics, see the recent article in the Scientific American: https://www.scientificamerican.com/article/infinity-category-theory-offers-a -birds-eye-view-of-mathematics1/ Application to ontology: Nearly everything we deal with in our daily lives involves processes in three dimensions plus time. The linear definitions in language and logic are usually drastically oversimplified approximations. The logic may seem to be precise, but that precision is often an illusion. As Lord Kelvin said, "Better a rough answer to the right question than an exact answer to the wrong question." John