diff --git a/generaldegree.tex b/generaldegree.tex index e612788..cba54be 100644 --- a/generaldegree.tex +++ b/generaldegree.tex @@ -4,6 +4,7 @@ \usepackage{amsthm} \usepackage{amsmath} \usepackage{tikz} +\usepackage[new]{old-arrows} \usetikzlibrary{cd, positioning, arrows.meta, decorations.pathmorphing, shapes.multipart, decorations.markings, calc} @@ -53,9 +54,9 @@ We will denote: We then have a commutative diagram: \begin{equation*} \begin{array}{ccc} - S_d & \longrightarrow & M_d \\ + S_d & \longhookrightarrow & M_d \\ \downarrow & & \downarrow \\ - K & \longrightarrow & \PP^2\setminus C_d \\ + K & \longhookrightarrow & \PP^2\setminus C_d \\ \end{array} \end{equation*} @@ -205,7 +206,7 @@ similarly to the previous case, in this line $x=1-z$. \end{proof} -Now that we have the retractions that allow us to retract $M_1$ into $S_1$, we will try to lift them in order to get a retraction from $M_d$ to $S_d$. +Now that we have the retractions that allow us to retract $M_1$ into $S_1$, we will lift them in order to get a retraction from $M_d$ to $S_d$. \begin{theorem} $S_d$ is a strong deformation retract of $M_d$. @@ -250,7 +251,7 @@ we can then write the retraction as $\bar{r}(x,t)=m(x,t)e^{2i\pi\theta(x,t)}$ wh For a $x=x_r+ix_i\in\CC$, $\bar{r}(x,t)=x_r+(1-t)ix_i$, we can write $m(x,t)=+\sqrt{x_r^2+(1-t)^2x_i^2}$ and $\theta(x,t)=\arctan\frac{(1-t)x_i}{x_r}$. -We can divide $\CC$ in $2d$ sectors of angle $\pi/d$ as in figure \ref{divisionC}. +We can divide $\CC$ in $2d$ sectors of angle $\pi/d$ as in figure \ref{divisionC}, where each of the sections will be homeomorphic to either the upper half complex plane or to the lower half. \begin{figure}[h] \begin{center} @@ -317,7 +318,7 @@ Then, we can see that $G(z,t)^d=\bar{r}(z^d,t)$, since: \bar{r}(z^d,t)&=&m(z^d,t)\exp^{i\arctan((1-t)\tan d\theta)}\\ \end{array} \end{equation} - +We can the write the lifting of $r_1$ as $\tilde{r}_1((x,y,z),t)=(G(x,t), G(y,t), G(z,t))$. Lastly, we are going to see how to lift $r_2$ in order to get a retraction from $M_d\cap\{x^d, y^d, z^d\in\RR\}$ into $S_d$. @@ -417,9 +418,9 @@ We denote as $\Delta$ the $\Delta-$complex $[v_0, v_1, v_2]$ that has $3$ vertic \begin{array}{ccccc} \Delta & \longleftrightarrow & S_1 & & \\ \uparrow& & \uparrow & & \\ - \Delta^d & \longleftrightarrow & S_d & \longrightarrow & M_d \\ + \Delta^d & \longleftrightarrow & S_d & \hookrightarrow & M_d \\ & & \downarrow & & \downarrow \\ - & & K & \longrightarrow & \PP^2\setminus C_d \\ + & & K & \hookrightarrow & \PP^2\setminus C_d \\ \end{array} \end{equation*} where $\Delta^d$ is a $\Delta-$complex that we are trying to find and identify with $S_d$, equivalently as what we have done for $d=1$. Since $S_d$ is a ramified cover of $S_1$ by the power to the $d$ map, we want $\Delta^d$ to be a ramified cover of $\Delta$ by the same map.