Tikz large bullet

Question

I'm trying to get some information on how to plot graphs from this very interesting and nice open book (Discrete Mathematics: An Open Introduction, Oscar Levin) and its source code.

This is the code copied and pasted from the original (without configuration!):

\documentclass{article}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
    \coordinate (A) at (90+360/5:1);
    \coordinate (B) at (90+2*360/5:1);
    \coordinate (C) at (90+3*360/5:1);
    \coordinate (D) at (90+4*360/5:1);
    \coordinate (E) at (90:1);

    \draw (A) -- (B) -- (C) -- (D) -- (E) -- (A);
    \foreach \x in {(A), (B), (C), (D), (E)}{
        \fill \x \v;
    }
\end{tikzpicture}
\end{document}

And this what I get:

There should be some initialization to get the vertices bigger as in the linked book:

I would prefer a direct link to the lines of the linked source code (referring to the initialization file and to the file containing the copied lines), so that in the future I can refer directly there.

Answer 1

You do not define \v but I suspect it may be a macro for a circle. Nevertheless, things can be simplified.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\tikzset{fancy ngon/.style={regular polygon,draw,minimum width=2cm,regular polygon sides=#1,alias=ngon,
append after command={foreach \XX in {1,...,#1} {(ngon.corner \XX) node[bullet]}}},
bullet/.style={circle,fill,inner sep=1.5pt,node contents={}}}
\begin{document}
\begin{tikzpicture}
    \coordinate (A) at (90+360/5:1);
    \coordinate (B) at (90+2*360/5:1);
    \coordinate (C) at (90+3*360/5:1);
    \coordinate (D) at (90+4*360/5:1);
    \coordinate (E) at (90:1);

    \draw (A) -- (B) -- (C) -- (D) -- (E) -- (A);
    \foreach \x in {(A), (B), (C), (D), (E)}{
        \fill \x circle[radius=2pt];
    }
\end{tikzpicture}

\begin{tikzpicture}
    \node[fancy ngon=5]{};
    \node[fancy ngon=6] at (3,0) {};
\end{tikzpicture}
\end{document}