Cfrgtkky

I created the following graph with vector symbol on edges:

I want to make the vectors larger without enlarging the text, so I devised a command:

newcommand{vecb}[1]{reflectbox{reflectbox{scalebox{2}[1.5]{ensuremath{vec{scalebox{0.5}[0.66]{ensuremath{#1}}}}}}}}

Which makes the arrow larger:

But if I use it in TikZ, it errors:

Use of XKV@resa doesn't match its definition.

Graph code:

begin{tikzpicture}

  GraphInit[vstyle=Normal]

  SetGraphUnit{1.5}

  tikzset{VertexStyle/.append style={rectangle}}



  Vertex[x=0,y=0]{John}

  Vertex[x=4.5,y=0]{London}

  Vertex[x=9,y=0]{England}

  Edge[style={->,>=triangle 45},label=$vec{residence}$](John)(London)

  Edge[style={->,>=triangle 45},label=$vec{capital}$](London)(England)

end{tikzpicture}

Why doesn't this work? How can this be fixed?

Using normal tikz with the positioning library, this can be simpler. I used a small trick to get the arrow using $overrightarrow{..}$. This arrows extends over the entire content, so I included only three letters inside the braces like this, $caoverrightarrow{pit}al$ such that the arrow becomes only three characters long.

documentclass[tikz,border=5pt]{standalone}

usetikzlibrary{positioning,arrows}

begin{document}



begin{tikzpicture}[blk/.style={draw, minimum height=2em}, >=triangle 45,thick]

node(j) [blk]{John}; 

node(l) [blk,right=10em of j]{London}; 

node(e) [blk,right=10em of l]{England};



draw [->] (j) -- node[fill=white]{$resoverrightarrow{ide}nce$} (l);

draw [->] (l) -- node[fill=white]{$caoverrightarrow{pit}al$} (e);

end{tikzpicture}



end{document}

Welcome to TeX.SE! So you are using TikZ and are afraid that you cannot add an arrow on top of some node text? No, I don't think there is an issue. ;-)

documentclass[tikz,border=3.14mm]{standalone}

usepackage{tkz-graph}

begin{document}

begin{tikzpicture}[vec/.style={inner ysep=3pt,path picture={

 draw[-latex,line width=0.4pt] ([yshift=-1.5pt,xshift=3pt]path picture bounding box.north west)

 --([yshift=-1.5pt,xshift=-3pt]path picture bounding box.north east);}}]

  GraphInit[vstyle=Normal]

  SetGraphUnit{1.5}

  tikzset{VertexStyle/.append style={rectangle}}



  Vertex[x=0,y=0]{John}

  Vertex[x=4.5,y=0]{London}

  Vertex[x=9,y=0]{England}

  Edge[style={->,>=triangle 45},label=$residence$,labelstyle=vec](John)(London)

  Edge[style={->,>=triangle 45},label=$capital$,labelstyle=vec](London)(England)

end{tikzpicture}

end{document}

I personally would not use math font for residence/capital.

pure tikz solution, vectors' arrows are drawn with tikz:

documentclass[tikz, border=3.141592mm]{standalone}

usetikzlibrary{arrows.meta, chains, positioning}



begin{document}

    begin{tikzpicture}[

node distance = 33mm,

  start chain = A going right,

   arr/.style = {very thick, -Triangle},

   lbl/.style = {rectangle, fill=white, name=lbl, inner ysep=3mm,

                 path picture={

                 draw[thick, -{Straight Barb[length=0.8mm,width=1.2mm]}]

                 ([shift={(-.2,-.15)}]lbl.north) -- ([shift={(.2,-.15)}]lbl.north);}

                },

   box/.style = {rectangle, draw, on chain=A, join=by arr}

                    ]

node[box] {John};

node[box] {London};

node[box] {England};

path   (A-1) -- node[lbl] {textit{residence}}  (A-2)

        (A-2) -- node[lbl] {textit{capital}}    (A-3);

end{tikzpicture}

end{document}

This might be another solution using tikz-cd. For an small arrow you can use (for example) the suggestion of @AboAmmar.

documentclass[a4paper,12pt]{article}



usepackage{amsmath}

usepackage{tikz-cd}

begin{document}

begin{tikzcd}

boxed{text{John}} arrow[rr, "overrightarrow{mathit{residence}}" description] &  & boxed{text{London}} arrow[rr, "overrightarrow{mathit{capital}}" description] &  & boxed{text{England}}

end{tikzcd}

end{document}