Air transportation in the Philippines local airlines in the Philippines which have a current air operator's certificate issued by the Civil Aviation Authority. Note: Destinations in bold indicate primary hubs, those in "italic" indicate secondary hubs, while those with regular font indicate focus cities. Air transportation in the Philippines Air transportation in the Philippines goes back to the early days of aviation prior to World War II, during the American colonial period of the Philippines. Currently, the Philippines has several registered airline companies, but they are mostly chartered. There are two main domestic airline groups doing business as Philippine Airlines and Cebu Pacific, with AirAsia
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