# All Questions

104 views

### The Borel construction of equivariant cobordism

In $K$ theory, the Borel construction of equivariant cohomology is somehow not the right one. The $G$-equivaraint $K$ theory of a point should be the representation ring of $G$, but $K(BG)$ is this ...
55 views

### If there is a finite R-module of finite inj dim, then R is Cohen [on hold]

I have a question about Exercise 3.1.24 of bruns herzog book,Cohen Macaulay rings,:If there is a finite R-module of finite injective dimension, M, then R is Cohen Macaulay ring. This is more general ...
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### Is this a valid way to prove that this infinite sum is divergent? [migrated]

I have the infinite sum: $$\sum_{n=1}^{\infty}\frac{1}{2(n+2)}$$ In this sum I observe that all instances of n is added with 2 before used. Therefor I would think i could do this ...
55 views

### Lim inf and lim sup for a specific sequence of sets [on hold]

Let the indicator function be defined as $$I(x) \triangleq \begin{cases} 1, & \quad x \geq 0 \\ 0, & \quad x < 0 \end{cases}$$ and $I_{\nu}(x) \in [0,1]$ be an approximation of the $I(x)$ ...
71 views

### Does positivity preserve compactness? [on hold]

Suppose $A$ and $B$ are operators on a (separable) Hilbert space $H$ and $A \leq B$. Is it true that if $B$ is compact then $A$ is compact too? If not, could you please show a counterexample?
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### Trivial Legendrian deformations defined by infinitesimal Sasakiautomorphisms

I'm reading the paper Y. Ohnita: On deformation of 3-dimensional certain minimal Legendrian submanifolds, Proceedings of The Thirteenth International Workshop on Differential Geometry and Related ...
18 views

### Boolean Algebra - Simplifying circuits [on hold]

Here is the question F = AB(CD + A~B + ~AD) + AD(C + ~D)‏ My attempt ABCD + ABA~B- + AB~AD + ADC + AD~D ....multiplying out the brackets = ABCD + A0 + 0BD + ADC + A0 .... X.~X = 0 = ABCD ...
256 views

### Invariant subsets of $z \mapsto z^2$

Where can I find an explicit construction of closed invariant subsets of the map $z \mapsto z^2$ on the unit circle? Furstenberg mentions that there are continuum of such disjoint minimal sets but ...
149 views