Geography of the Philippines the Philippines, the Sierra Madre, stretching from Quezon province in the south to Cagayan in the north. 80 percent of the mountain range is tropical rainforest, which is diminishing from rampant illegal logging activity. The range serves as the eastern wall of Luzon Island that protects inhabitants from tropical cyclones usually coming from the Pacific Ocean. The largest plain of the nation is situated in the Central Luzon region and produces most of the national rice supply, earning itself the nickname ""Rice Bowl of the Philippines"". The plains encompass the provinces of Bulacan, Nueva Ecija, Pampanga, Tarlac and Pangasinan. South
Lie theory Lie theory In mathematics, the researcher Sophus Lie ( ) initiated lines of study involving integration of differential equations, transformation groups, and contact of spheres that have come to be called Lie theory. For instance, the latter subject is Lie sphere geometry. This article addresses his approach to transformation groups, which is one of the areas of mathematics, and was worked out by Wilhelm Killing and Élie Cartan. The foundation of Lie theory is the exponential map relating Lie algebras to Lie groups which is called the Lie group–Lie algebra correspondence. The subject is part of differential geometry since Lie