... Preface The Dictionary of Classical and Theoretical Mathematics, one volume of the ComprehensiveDictionary of Mathematics, includes entries from the fields of geometry, logic, number theory,set theory, ... length, then there is an orthonormal frame(T,U,V) defined along the curve called Dar-boux’s frame. The first vector, T = γ(s),is the unit tangent vector to the curve. The vectorV = ν(γ (s)) is the ... the language of the propositional logic, can deter-mine whether or not the string is a well-formedformula, and if it is, can determine whether ornot the well-formed formula is a tautology. Asanother...