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If you're into this stuff, I really like this book on Galois theory: https://www.worldcat.org/title/classical-introduction-to-galois-theory/oclc/864911918 http
by jordigh 5y ago
If you're into this stuff, I really like this book on Galois theory:
https://www.worldcat.org/title/classical-introduction-to-galois-theory/oclc/864911918 https://www.worldcat.org/title/classical-introduction-to-gal...
The reason I like this book is that it is very computational, in the spirit of Galois's original discoveries. Modern treatment of Galois theory has been greatly coloured by Emil Artin's reformulation of the subject: the Galois group is nowadays primarily taught to undergrads as being a group of automorphisms of a field extension instead of being primarily the computational object of the permutations of the roots of a polynomial.
Artin's approach has merit, of course. The extra level of abstraction generalises to much more than just simple algebraic extensions of the rationals. However, I think the historical approach in this case is more instructive. Seeing lots of calculations before the abstractions gives you a better sense of what's being abstracted away.
- dmch-1 5y agoThere is Artin's approach, and then there is a more abstract approach by Grothendieck relating to the fundamental group of algebraic topology. In the movie Beautiful mind there is a scene, where a student tells John Nash that he can proof that 'Galois extensions are the same as covering spaces'. This follows from the Grothendieck's approach. However the analogy between Galois extessions and the fundamental group was known even before Grothendieck. Then there are even more general approaches in the category theory setting. Today these generalisations are taught indeed without much regard to the computational spirit of 19th century mathematics. They have their merit as you say, but I agree understanding the computational aspects are instructive in fully appreciating the generalisations and analogies.