FLEXIBILITY IN AGRICULTURE

This paper considers the determinants of two dimensions of flexibility, the flexibility in adjusting aggregate output over time ("tactical flexibility") as well as the ability to switch quickly between products ("operational flexibility"). Econometric analysis of a sample of 40,000 farms in Upper-Austria for the period 1980 to 1990 suggests that larger full-time farms operated by younger, better educated farm operators are more flexible, ceteris paribus. The results further indicate a significant and negative interrelationship between tactical and operational flexibility.Farm Management, Industrial Organization,

The closure constraint for the hyperbolic tetrahedron as a Bianchi identity

The closure constraint is a central piece of the mathematics of loop quantum gravity. It encodes the gauge invariance of the spin network states of quantum geometry and provides them with a geometrical interpretation: each decorated vertex of a spin network is dual to a quantized polyhedron in $\mathbb{R}^{3}$. For instance, a 4-valent vertex is interpreted as a tetrahedron determined by the four normal vectors of its faces. We develop a framework where the closure constraint is re-interpreted as a Bianchi identity, with the normals defined as holonomies around the polyhedron faces of a connection (constructed from the spinning geometry interpretation of twisted geometries). This allows us to define closure constraints for hyperbolic tetrahedra (living in the 3-hyperboloid of unit future-oriented spacelike vectors in $\mathbb{R}^{3,1}$) in terms of normals living all in $SU(2)$ or in $SB(2,\mathbb{C})$. The latter fits perfectly with the classical phase space developed for $q$-deformed loop quantum gravity supposed to account for a non-vanishing cosmological constant $\Lambda>0$. This is the first step towards interpreting $q$-deformed twisted geometries as actual discrete hyperbolic triangulations.Comment: 31 page