- Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or logical truths. It studies how conclusions follow from premises due to the structure of arguments alone, independent of their topic and content. Informal logic is associated with informal fallacies, critical thinking, and argumentation theory. It examines arguments expressed in natural language while formal logic uses formal language. When used as a countable noun, the term “a logic” refers to a logical formal system that articulates a proof system. Logic plays a central role in many fields, such as philosophy, mathematics, computer science, and linguistics.
- Star Tales - Norma (ianridpath.com)
Norma is one of the constellations introduced by the French astronomer Nicolas Louis de Lacaille following his mapping of the southern skies in 1751–52. It consists of faint stars between Ara and Lupus that were not catalogued by Ptolemy. On his 1756 planisphere Lacaille called it l’Equerre et la Regle, although in his accompanying star catalogue the name was given simply as l’Équerre. In the notes to his catalogue he described it as representing an architect’s set-square and ruler.