Orsdxy

I'm translating a manual of syntax and they have some examples of non-valid structures. The first one I was able to reproduce, but not the second.

This is what I'm trying to reproduce:

My current code is the following:

documentclass{article}

usepackage{tikz-qtree}



begin{document}



begin{figure}[h]

centering



textbf{a}) begin{tikzpicture}[level distance=30pt,sibling distance=5mm] 

tikzset{every tree node/.style={align=center,anchor=base}}

tikzset{level 1+/.style={level distance=2baselineskip}}

tikzset{frontier/.style={distance from root=6baselineskip}}

Tree [.a [.b ] [.c ] ]

begin{scope}[grow'=up,yshift=-1.7cm]

Tree [.d [.b ] [.c ] ]

end{scope}

end{tikzpicture}qquad



textbf{b}) begin{tikzpicture}[level distance=30pt,sibling distance=5mm] 

Tree ??????????????????

end{figure}



end{document}

These do not necessarily look like trees, so I would not necessarily recommend to use a library specialized on trees for that.

documentclass{article}

usepackage{subfig}

usepackage{tikz}

usetikzlibrary{matrix}

begin{document}



begin{figure}[h]

centering

subfloat{begin{tikzpicture}

matrix (mat) [matrix of nodes,column sep=1em,row sep=1em,

 nodes={align=center,inner sep=2pt},ampersand replacement=&]

 {

 & a & \

 b & & c\

 & d &\

 };

 draw (mat-2-1.north) -- (mat-1-2.south) -- (mat-2-3.north)

 (mat-2-1.south) -- (mat-3-2.north) -- (mat-2-3.south);

end{tikzpicture}}

qquad

subfloat{begin{tikzpicture}

matrix (mat) [matrix of nodes,column sep=1em,row sep=1em,

 nodes={align=center},ampersand replacement=&]

 {

 & a & \

 b & & c\

 e &  & d\

 };

 draw (mat-2-1.north) -- (mat-1-2.south) -- (mat-2-3.north)

 (mat-2-1) -- (mat-3-3) (mat-2-3) -- (mat-3-1);

end{tikzpicture}}

end{figure}

end{document}

An alternative to marmot's nice answer:

documentclass{article}

usepackage{tikz}

usepackage{subcaption}

begin{document}

begin{figure}

    centering

    begin{subfigure}[t]{0.5textwidth}

        centering

        begin{tikzpicture}[y=1.5cm]

            node (a) at (0,0) {a};

            node (b) at (-1,-1) {b};

            node (c) at (1,-1) {c};

            node (d) at (0,-2) {d};

            draw (b.north)--(a.south)--(c.north);

            draw (b.south)--(d.north)--(c.south);

        end{tikzpicture}  

        caption{}

    end{subfigure}%

    begin{subfigure}[t]{0.5textwidth}

        centering

        begin{tikzpicture}[y=1.5cm]

            node (a) at (0,0) {a};

            node (b) at (-1,-1) {b};

            node (c) at (1,-1) {c};

            node (d) at (1,-2) {d};

            node (e) at (-1,-2) {e};

            draw (b.north)--(a.south)--(c.north);

            draw (b.south)--(d.north);

            draw (c.south)--(e.north);

        end{tikzpicture}  

        caption{}

    end{subfigure}

end{figure}

end{document}

But I prefer this

documentclass{article}

usepackage{tikz}

usepackage{subcaption}

begin{document}

begin{figure}

    centering

    begin{subfigure}[t]{0.5textwidth}

        centering

        begin{tikzpicture}[y=1.5cm,every node/.style={circle,draw,minimum size=0.75cm}]

            node (a) at (0,0) {a};

            node (b) at (-1,-1) {b};

            node (c) at (1,-1) {c};

            node (d) at (0,-2) {d};

            draw (b)--(a)--(c)--(d)--(b);

        end{tikzpicture}  

        caption{}

    end{subfigure}%

    begin{subfigure}[t]{0.5textwidth}

        centering

        begin{tikzpicture}[y=1.5cm,every node/.style={circle,draw,minimum size=0.75cm}]

            node (a) at (0,0) {a};

            node (b) at (-1,-1) {b};

            node (c) at (1,-1) {c};

            node (d) at (1,-2) {d};

            node (e) at (-1,-2) {e};

            draw (d)--(b)--(a)--(c)--(e);

        end{tikzpicture}  

        caption{}

    end{subfigure}

end{figure}

end{document}