Laburnum Laburnum Laburnum, sometimes called golden chain or golden rain, is a genus of two species of small trees in the subfamily Faboideae of the pea family Fabaceae. The species are "Laburnum anagyroides"—common laburnum and "Laburnum alpinum"—alpine laburnum. They are native to the mountains of southern Europe from France to the Balkans. Some botanists include a third species, "Laburnum caramanicum", but this native of southeast Europe and Anatolia is usually treated in a distinct genus "Podocytisus", more closely allied to the "Genisteae" (brooms). The "Laburnum" trees are deciduous. The leaves are trifoliate, somewhat like a clover; the leaflets are typically long
Spanning tree and "routing loops", many routing protocols designed for such networks—including the Spanning Tree Protocol, Open Shortest Path First, Link-state routing protocol, Augmented tree-based routing, etc.—require each router to remember a spanning tree. A special kind of spanning tree, the Xuong tree, is used in topological graph theory to find graph embeddings with maximum genus. A Xuong tree is a spanning tree such that, in the remaining graph, the number of connected components with an odd number of edges is as small as possible. A Xuong tree and an associated maximum-genus embedding can be found in polynomial time. A tree is