Just to check, I have three math textbooks from my college days that include the definition of an ideal, and none of them attempt to exclude the ring itself from the definition.
The obvious compromise is to introduce the concept of a proper ideal as an ideal that is a proper subset, and to use that when you need to exclude the ring itself. E.g., a maximal ideal is a proper ideal that is maximal with respect to inclusion.
If you don't include the whole ring as an ideal, you can't even define ideal addition, etc. I took an algebra class once from a professor who decided to define "ideal" to mean "proper ideal". After a few weeks he had to give it up because it just became too much trouble for reasons like that; he had to too often say "possibly improper ideal", i.e., this convention had the opposite effect he intended! I can't think of any other source I've seen use that convention.
All of algebraic geometry (a very popular branch of mathematics for studying rings) is built on the lattice of ideals. There is no way of giving a ring this structure without the ring itself being the top element of this lattice.
What you probably mean to say is that there are sources that do not treat R as a prime ideal of itself.
If the only subspaces are single points then the space is itself a point.
mtsolitary•1d ago
tux3•1d ago
You sometimes hear people say that math is tautological. But regardless of whether it's all just an elaborate rephrasing of the axioms, it's quite beautiful.
math_dandy•1d ago
mathgradthrow•1d ago
This is not my most popular opinion, but probably the most consequential invention of the last 400 years was the set. Suddenly all mathematical knowledge could be verified in one framework. Physicists had a target in which to state their models.
If you could state your hypothesis in the language of mathematics, "everyone" knew exactly what you meant by it, and how to go about testing your claims, or proving them, if they happened to be about mathematics itself.
Calculus was invented in 1690ish, physicists like to claim that this was the most important advance in physics, but quantum mechanics and relativity didn't happen until dedekind invented the real numbers, 200 years later.
It turns out that knowing what you're talking about matters.
gjm11•1d ago
A more plausible claim: the general move towards greater rigour in mathematics, one of whose expressions was Dedekind's formalization of the real numbers, improved the state of mathematical understanding in ways that were necessary for the arrival of quantum physics and relativity. E.g., to do quantum physics you want the notion of "vector space"; to do general relativity you want the notion of "Riemannian manifold"; to do special relativity maybe you want to have encountered the "Erlangen programme".
But I'm not 100% convinced. It's not unusual for physicists to make use of mathematical notions that they don't have precise definitions of. E.g., I'm not sure anyone has an entirely satisfactory formal account of "path integrals"; string theory may or may not turn out to have anything to do with how the universe actually works, but if it doesn't it probably won't be because we don't have a complete account of what it actually is. Newton managed to do pretty impressive things with calculus before anyone had a really convincing definition of such advanced notions as, er, "derivative".
mathgradthrow•1d ago
Sharlin•23h ago
mathgradthrow•10h ago
chermi•21h ago
mathgradthrow•20h ago
chermi•9h ago
aleph_minus_one•1d ago
According to a professor, "trivial" means: "If this is not trivial for you, you should see this as a clear signal that you should take this course seriously instead of slacking of, or even that you simply are in the wrong course."
tekla•1d ago
kevinventullo•1d ago
xelxebar•1d ago
Math does feel like that a lot of the time. Once you've tree-searched proof space and found the connection, you can usually spend way less time proving it the next time around.
gosub100•1d ago
JadeNB•1d ago
I am skeptical that this uniquely identifies a book (unless you mean the book "Linear Algebraic Groups" by the author called Springer, rather than the publisher called Springer, in which case it's definitely not the way to start learning group theory!).
gosub100•1d ago
layer8•1d ago
It’s a graduate-level text, to be fair.
mwcremer•1d ago
xelxebar•1d ago
zem•21h ago
downboots•1d ago
aleph_minus_one•1d ago
In my opinion: the difference between a complex subject and one formally expressed in a complex way is that in the former, the results that you get are really deep (understanding them at the end feels like a spiritual experience).
mtsolitary•1d ago
fn-mote•1d ago
My experience is that mastery means more like "you have a mental model which gives you 'intuitive' reasons to accurately classify things as true/false and provides some motivation for the reasoning".
An example: you see someone has solved a degree 4 equation by repeatedly applying the quadratic equation, getting 8 solutions. "No way."
Another example: watch a famous baking show and you see somebody put a bunch of different sized pieces of bread in the oven at the same time. Right away: "aren't they going to cook at different rates?" Sure enough, some burned, some raw.
layer8•1d ago
mtsolitary•15h ago
bubblyworld•1d ago
If your ring has only two ideals then the trivial ideal is maximal, and thus your ring is already a field!
The more you know, the more "shortcuts" you start seeing, I guess.
srean•1d ago
almostgotcaught•1d ago
EDIT: if you hate "a monad is a monoid in the category of endofunctors" then you also hate "definitions should be hard and theorems easy".
andrewflnr•1d ago
Though maybe the way this course would work is in fact by proceeding through a series of easy but explicitly flawed definitions, and proving both real results and nonsense from them, so you see why the real definition is justified.
almostgotcaught•1d ago
yes so then you want proofs that actually exercise real machinery instead of playing the shell game of "an X is a Y and a Y is a Z, and has ABC properties, there for X has ABC properties"; you want a proof that goes through the process of using properties ABC to build Y from Z and X from Y (or something akin to that).
definitions aren't for people learning math, they're for people using math ie practising professional mathematicians that are proving more theorems; Hausdorff didn't invent "Hausdorff spaces", he used/worked with various properties of topological spaces and then when the next person came along and needed to right another paper on top, that person invented "Hausdorff space".
dmkolobov•1d ago
However, the more I’ve learned about category theory, the more I’ve understood it as a way of defining what things are and what properties follow from those definitions.
Like, a monad really doesn’t have meaning beyond “monoid in the category of endofunctors”. The same is true for monoids and endofunctors: it’s all about the properties of those objects.
In the context of programming, we can impose all kinds of meaning, but the definitions and laws are really what makes it all work when you piece it together.
I guess my approach is to suffer through it until some understanding is gleaned, which admittedly isn’t very satisfying or easy haha.
almostgotcaught•23h ago
VladVladikoff•1d ago
xelxebar•1d ago
"Applications of Abstract Algebra with Maple and MATLAB" by Klinger, Sigmon, and Stitzinger is apparently good for those with an engineering background: https://www.maplesoft.com/books/details.aspx?id=624.
If you're committed, then any introductory text on abstract algebra or group theory might capture your interest.
I would recommend starting with applications or something as close to your wheelhouse as possible just to stay motivated. Abstract algebra, in particular, is known for requiring quite a lot of machinery before obviously connecting with other things, which can feel like an onslaught unless you're inherently interested.
Have fun though! It's really one of the deepest subjects in modern math, IMHO. Almost every field has been affected by it's results.
VladVladikoff•17m ago