Mathematics – Quantum Algebra
Scientific paper
1998-04-22
Mathematics
Quantum Algebra
51 pages; LaTeX with XY-Pic diagrams
Scientific paper
We study what happens when coherence fails. Categories with a tensor product and a natural associativity isomorphism that does not necessarily satisfy the pentagon coherence requirements (called associative categories) are considered. Categorical versions of associahedra where naturality squares commute and pentagons do not, are constructed (called Catalan groupoids, $\An$). These groupoids are used in the construction of the free associative category. They are also used in the construction of the theory of associative categories (given as a 2-sketch). Generators and relations are given for the fundamental group, $\pi(\An)$, of the Catalan groupoids -- thought of as a simplicial complex. These groups are shown to be more than just free groups. Each associative category, $B$, has related fundamental groups $\pi(\bf B_n)$ and homomorphisms $\pi(P_n):\pi(\An) \longrightarrow \pi(\bf B_n)$. If the images of the $\pi(P_n)$ are trivial, i.e. there is only one associativity path between any two objects, then the category is coherent. Otherwise the images of $\pi(P_n)$ are obstructions to coherence. Some progress is made in classifying noncoherence of associative categories.
No associations
LandOfFree
Obstructions to Coherence: Natural Noncoherent Associativity does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Obstructions to Coherence: Natural Noncoherent Associativity, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Obstructions to Coherence: Natural Noncoherent Associativity will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-474280