diff --git a/docker-compose.yaml b/docker-compose.yaml index 01be999..8570447 100644 --- a/docker-compose.yaml +++ b/docker-compose.yaml @@ -3,7 +3,7 @@ services: build: context: ./ dockerfile: ./Dockerfile - image: trance0/notenextra:v1.1.14 + image: trance0/notenextra:v1.1.15 restart: on-failure:5 ports: - 13000:3000 diff --git a/pages/CSE559A/CSE559A_L23.md b/pages/CSE559A/CSE559A_L23.md new file mode 100644 index 0000000..870e605 --- /dev/null +++ b/pages/CSE559A/CSE559A_L23.md @@ -0,0 +1,15 @@ +# CSE559A Lecture 23 + +## DUSt3r + +Dense and Unconstrained Stereo 3D Reconstruction of arbitrary image collections. + +[Github DUST3R](https://github.com/naver/dust3r) + + + + + + + + diff --git a/pages/Math416/Math416_L24.md b/pages/Math416/Math416_L24.md new file mode 100644 index 0000000..723298b --- /dev/null +++ b/pages/Math416/Math416_L24.md @@ -0,0 +1,159 @@ +# Math416 Lecture 24 + +## Continue on Generalized Cauchy's Theorem + +### Homotopy + +A homotopy between two curves $\gamma_0, \gamma_1 : [0, 1] \to \mathbb{C}$ is a continuous map $H : [0, 1] \times [0, 1] \to \mathbb{C}$ such that $H(z, 0) = \gamma_0(z)$ and $H(z, 1) = \gamma_1(z)$ for all $z \in [0, 1]$. + +#### Lemma: + +Let $\Omega$ be open in $\mathbb{C}$, Let $\gamma_0, \gamma_1$ be closed contour, homotopic in $\Omega$. Then $\operatorname{ind}_{\gamma_0} (z) = \operatorname{ind}_{\gamma_1} (z)$ for all $z \in \Omega$. + +Proof: + +Let $H(s,t)$ be a homotopy between $\gamma_0$ and $\gamma_1$. Let $z_0\in \mathbb{C} \setminus \Omega$. + +Defined $\phi:[0,1]\times[0,1]\to \mathbb{C}\setminus \{0\}$, $\phi(s,t)=H(s,t)-z_0$. + +By [Technical Lemma](https://notenextra.trance-0.com/Math416/Math416_L23#lemma-912-technical-lemma), $\exists$ continuous $\psi:[0,1]\times[0,1]\to \mathbb{C}$ such that $e^{\psi}=\phi$. + +For each $t$, $\gamma_t(s)=H(s,t)$ is a closed curve. + +$\operatorname{ind}_{\gamma_t}(z_0)=\frac{1}{2\pi i}\left[\psi(1,t)-\psi(0,t)\right]$. + +This is continuous (in $t$), integer valued, thus constant. + +QED + +#### Theorem 9.14 Homotopy version of Cauchy's Theorem + +Let $\Omega$ be open, $\gamma_0, \gamma_1$ be two piecewise continuous curves in $\Omega$ that are homotopic. + +Then $\int_{\gamma_0} f(z) \, dz = \int_{\gamma_1} f(z) \, dz$ for all $f\in O(\Omega)$. + +Proof: + +$\Gamma=\gamma_0-\gamma_1$, then $\operatorname{ind}_{\Gamma}(z)=0$ for all $z\in \mathbb{C}\setminus \Omega$. + +QED + +#### Corollary of Theorem 9.14 + +If $\gamma_0$ is null-homotopic in $\Omega$ (i.e. $\gamma_0$ is homotopic to a point), then $\int_{\gamma_0} f(z) \, dz = 0$ for all $f\in O(\Omega)$. + +## Chapter 10: Further development of Complex Function Theory + +### Simple connectedness + +#### Definition (non-standard) simply connected + +Let $\Omega$ be a domain in $\mathbb{C}$. We say $\Omega$ is simply connected if $\overline{\mathbb{C}}\setminus \Omega$ is connected. ($\overline{\mathbb{C}}=\mathbb{C}\cup \{\infty\})$ + +Example: + +disk is simply connected. + +annulus is not simply connected. + +$\mathbb{C}$ is simply connected. + +Any convex domain is simply connected. + +> Standard definition: $\Omega$ is simply connected if every closed curve in $\Omega$ is null-homotopic in $\Omega$. + +#### Theorem of equivalent definition of simply connected + +For open connected subsets of $\mathbb{C}$, the standard definition and the non-standard definition are equivalent. + +Proved end of book. + +#### Proposition for simply connected domain + +$\Omega$ is simply connected $\iff$ every contour in $\Omega$ has winding number $0$ about every point in $\mathbb{C}\setminus \Omega$. + +Proof: + +If $\Omega$ is simply connected, let $\gamma$ be a curve in $\Omega$, then $\operatorname{ind}_{\gamma}(z)=0$ for all $z$ in the unbounded component of $\overline{\mathbb{C}}\setminus \Omega$. This contains all of $\mathbb{C}\setminus \Omega$. + +Conversely, assume $\Omega$ is not simply connected, then $\exists K\cup L=\overline{\mathbb{C}}\setminus \Omega$, where $K$ and $L$ are disjoint closed, without loss of generality, assume $\infty\in L$. + +Let $H=\Omega\cup K=\mathbb{C}\setminus L$. + +$H$ is open, $K$ is compact subset of $H$, so by [Separation Lemma](https://notenextra.trance-0.com/Math416/Math416_L23#separation-lemma), $\exists \gamma\in H\setminus K=\Omega$ such that $K\subset \operatorname{int}(\gamma)$. + +#### Theorem 10.3 Cauchy's Theorem for simply connected domain + +corollary of Proposition for simply connected domain + +Let $\Omega$ be a simply connected domain, let $\gamma$ be a closed curve in $\Omega$. Then $\int_{\gamma} f(z) \, dz = 0$ for all $f\in O(\Omega)$. + +Proof: + +Know that is true if $\operatorname{ind}_{\gamma}(z)=0$ for all $z\in \mathbb{C}\setminus \Omega$. + +By Proposition, $\Omega$ is simply connected $\iff$ every closed curve in $\Omega$ has winding number $0$ about every point in $\mathbb{C}\setminus \Omega$. + +So the result is true. + +QED + +#### Theorem 10.4-6 + +The following condition are equivalent: + +1. $\Omega$ is simply connected. +2. every holomorphic function on $\Omega$ has a primitive $g$, i.e. $g'(z)=f(z)$ for all $z\in \Omega$. +3. every non-vanishing holomorphic function on $\Omega$ has a holomorphic logarithm. +4. every harmonic function on $\Omega$ has a harmonic conjugate. + +Proof: + +$(1)\iff (2)$: + +First we show $(1)\implies (2)$. + +Assume $\Omega$ is simply connected. + +Define $g(z)=\int_{z_0}^{z} f(w) \, dw$ for $z_0\in \Omega$ fixed. Then by Cauchy's Theorem, this definition does not depend on the path. + +$\frac{g(z+h)-g(z)}{h}=\frac{1}{h}\left[\int_{z}^{z+h} f(w) \, dw\right]$ + +$\frac{1}{h}\left[\int_{z}^{z+h} f(w) \, dw\right]\to f(z)$ as $h\to 0$. + +So on $[z,z+h]\subset \Omega$, if $|f(w)-f(z)|<\epsilon$, then $|\frac{g(z+h)-g(z)}{h}-hf(z)|