Durif The vine is a popular planting in Lake, Mendocino, Sonoma, Napa, Monterey and San Joaquin County. In addition to being produced as a varietal wine, the grape is sometimes blended with Zinfandel. In years when heavy rain or excess sun has weakened the quality or yield of Cabernet Sauvignon or Pinot noir plantings, Petite Sirah may also be used as a blending partner to strengthen the wine. The average age of Petite Sirah vines tends to be older than that of most Californian vines. As of December 2007, the TTB lists both Petite Sirah and Durif in 27 CFR §
History of manifolds and varieties spaces with a differentiable or topological structure, while "variety" refers to spaces with an algebraic structure, as in algebraic varieties. In Romance languages, manifold is translated as "variety" – such spaces with a differentiable structure are literally translated as "analytic varieties", while spaces with an algebraic structure are called "algebraic varieties". Thus for example, the french word "" means topological manifold. In the same vein, the Japanese word "" (tayōtai) also encompasses both manifold and variety. ("" (tayō) means various.) Ancestral to the modern concept of a manifold were several important results of 18th and 19th century mathematics. The oldest