The A∞ T-system, also called the octahedron recurrence, is a dynamical recurrence relation. It can be realized as mutation in a coefficient-free cluster algebra (Kedem 2008, Di Francesco and Kedem 2009). We define T-systems with principal coefficients from cluster algebra aspect, and give combinatorial solutions with respect to any valid initial condition in terms of partition functions of perf...

amount of information about what contemporaries felt they knew and what they did in actual practice. The first twothirds of the book covers such topics as remedies, diseases, healthy living, surgery and the knowledge, prevention and cure of the plague. And through this Part I, Wear addresses the similarities, differences, continuities and changes reflected in the ideas and practices of learned ...