Projective space Definition and 19 Threads

QM uses separable Hilbert spaces as model to represent quantum system's states. Take for instance a 1/2-spin particle: its quantum pure state is represented by a ray in the abstract Hilbert space ##\mathcal H_2## of dimension 2. Take an observable represented by an Hermitian unitary operator...

I'd like to discuss some aspects of quantum systems' state space from a mathematical perspective. Take for a instance a qubit, e.g. a two-state quantum system and consider the set of its pure states. This set as such is a "concrete" set, namely the "bag" containing all the qubit's pure states...

Let #F# be a field and consider the projective space of dimension #n# over it with added the point #0#. It seems to me that there is a valid definition of multiplication by just entrywise multiplicating the elements. Of course both can be multiplied by #x \in F# but that goes for the product as...

Let ##u## be a generator of ##H^1(\mathbb{R} P^\infty; \mathbb{F}_2)##. Prove the relations $$\text{Sq}^i(u^n) =\binom{n}{i} u^{n+i}$$

Suppose you have the map $$\pi : \mathbb{R}^{n+1}-\{0\} \longrightarrow \mathbb{P}^n$$. I need to prove that the map is differentiable. But this map is a chart of $$\mathbb{P}^n$$ so by definition is differentiable? MENTOR NOTE: fixed Latex mistakes double $ signs and backslashes needed for math

Hello! I am reading "Differential Geometry and Mathematical Physics" by Rudolph and Schmidt. And they have and example of manifold (projective space). I believe that there is a typo in the book, but perhaps I miss something deep. Definitions are the following $$\mathbb{K}^n_\ast=\{\mathbf{x}\in...

I am following the proof to show that the complex torus is the same as the projective algebraic curve. First we consider the complex torus minus a point, punctured torus, and show there is a biholomorphic map or holomorphic isomorphism with the affine algebraic curve in ##\mathbb{C}^2##...

Homework Statement Let P(W) be a projective space whose dimension is greater than or equal to 2 and let three non-colinear projective points, [v_{1}],[v_{2}],[v_{3}]\in P(W) . Prove that there is a projective plane in P(W) containing all three points. Homework EquationsThe Attempt at a...

I firstly learned about duality in context of differentiable manifolds. Here, we have tangent vectors populating the tangent space and differential forms in its co-tangent counterpart. Acting upon each other a vector and a form produce a scalar (contraction operation). Later, I run into the...

It is said that curves of the second order which we usually refer to as ellipse, parabola and hyperbola, i. e. conics, are all represented on projective plane by closed curves (oval curve), which means there is no distinction between them. Why is it? Projective space can, in principle, be...

Hi everybody, I want to ask if there are big differences consider algebraic objects in the projective or in the projective space with only positive coordinates? I know that the question is generic (so permit the discussion ... ). I am interested to know what happen to classical invariants if...

Just reviewing some QM again and I think I'm forgetting something basic. Just consider a qubit with basis {0, 1}. On the one hand I thought 0 and -0 are NOT the same state as demonstrated in interference experiments, but on the other hand the literature seems to say the state space is...

Dear all, I am not very experienced in this field, so, I have a rather simple question :smile: -Consider a linear vector space V of dimension 4. -Prescribe that, if two vectors in V differ by a nonvanishing constant, they belong to the same equivalence class. -Put together all these...

Hi, I am am currently taking a second course in geometry, the first part of the course concerns projective geometry, and I feel I'm not getting the picture. I would like to know what the motivation for the development of projective geometry is. What picture you guys have in your head of...

So I have been tasked with what is likely a very simple problem, but have forgotten so much complex analysis that I would like to very the problem. Let \mathbb{CP}^n denote the n-dimensional complex projective space. We want to show that the quotient map \pi: \mathbb C^{n+1}\setminus\{0\}...

I've been thinking...and am starting to think that I don't understand complex projective space...So, it's defined as ( Cn+1 \{0,0} / C\{0} ). Now, I think this is just the set of planes in 4 space that pass through the origin... and one can consider how they would all intersect a 3 sphere and...

Just like you can create the ilusion of superluminal motion by projecting a flashlight into a wall, some strings would be projected into tachyons. Has anyone heard or thought about that?

I have a question about complex projective space... specifically CP1 which can be thought of as the action of C on C^2\{0} which gives rise to the equivalence classes of "lines" passing through the origin in C^2 (but not including the 0) Now, any vector in complex space, when multiplied by the...

What is the relationship betwenn RP^2 and CP? Espesicially, why are their stenographic representations different? As far as I understand the stenographic representation for RP^2 goes like that: a sphere with antipodal points identified is put above the R^2 plane, lines through the origin...