start = e:expressao {return "<math>"+String(e)+"</math>"}

expressao = p:parcela "+" e:expressao 
	{return p+" <mo> + </mo> "+ e}
    / parcela

parcela = f:fator "/" t:parcela
	{return "<mfrac> "+f+" "+t+"</mfrac>";}
	/ fator

fator = literal / "(" e:expressao ")" {return "<mrow> "+e+" </mrow>";}

literal = number / identifier

number = digit+ {return "<mn> "+text()+" </mn>"}

identifier = (letter / capital) (letter / capital / digit)*
	{return "<mi> "+text()+" </mi>"}

digit = [0-9]

capital = [A-Z]

letter = [a-z]

_ "whitespace"
  = [ \t\n\r]*