I'm making my thesis in Lyx, and i need to write theorems, definitions, etc; but its necesary that appear like Teorema, Lema, Definición, etc.

I selected the document's language in spanish, the encoding is latin1, and the Theorems(AMS), Theorems(AMS-Extended) and Theorems(By Chapter).

The problems it's the definitions for the theorems still in Theorem, Definition, etc,

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Textclass specific LaTeX commands. \theoremstyle{plain} \ifx\thechapter\undefined \newtheorem{thm}{Theorem} \else \newtheorem{thm}{Theorem}[chapter] \fi \theoremstyle{definition} \newtheorem{defn}[thm]{Definition}

The preamble is this, (copy-paste from the source view)

% Preview source code %% LyX 1.6.2 created this file. For more info, see http://www.lyx.org/. %% Do not edit unless you really know what you are doing. \documentclass[12pt,oneside,english,spanish]{book} \usepackage[T1]{fontenc} \usepackage[latin1]{inputenc} \usepackage[letterpaper]{geometry} \geometry{verbose,tmargin=3cm,bmargin=3cm,lmargin=3.5cm,rmargin=3cm} \setcounter{secnumdepth}{3} \setcounter{tocdepth}{3} \usepackage{color} \usepackage{verbatim} \usepackage{textcomp} \usepackage{amsthm} \usepackage{relsize} \usepackage{graphicx} \usepackage{setspace} \usepackage{amssymb} \onehalfspacing \makeatletter %%%%%%%%%%%%%%%%%%%%%%%%%%%%%% LyX specific LaTeX commands. \DeclareRobustCommand{\lyxmathsym}[1]{\ifmmode\begingroup\def\b@ld{bold} \def\rmorbf##1{\ifx\math@version\b@ld\textbf{##1}\else\textrm{##1}\fi} \mathchoice{\hbox{\rmorbf{#1}}}{\hbox{\rmorbf{#1}}} {\hbox{\smaller[2]\rmorbf{#1}}}{\hbox{\smaller[3]\rmorbf{#1}}} \endgroup\else#1\fi} %% A simple dot to overcome graphicx limitations \newcommand{\lyxdot}{.} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Textclass specific LaTeX commands. \theoremstyle{plain} \ifx\thechapter\undefined \newtheorem{thm}{Theorem} \else \newtheorem{thm}{Theorem}[chapter] \fi \theoremstyle{definition} \newtheorem{defn}[thm]{Definition} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%% User specified LaTeX commands. %%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%Paquetes \usepackage[Glenn]{fncychap} \usepackage{graphicx} \usepackage{amsmath} \usepackage[spanish]{babel} \usepackage[latin1]{inputenc} \usepackage{babelbib} \usepackage{fancyhdr} %%%%%%%%%%%%% %% Encabezados %%%%%%%%%%%%% \pagestyle{fancy} \fancyhead{} \fancyhead[CE]{\scriptsize \leftmark} \fancyhead[CO]{\scriptsize \rightmark} \fancyhead[LE,RO]{\thepage} \fancyfoot{} \renewcommand{\headrulewidth}{0.9pt} %%%%%%%%%%%%% %% Estilos de teoremas % \swapnumbers %\theoremstyle{plain} %\newtheorem{teorema}{Teorema}%[section] % \theoremstyle{definition} % \newtheorem{definicion}[teorema]{Definici\'{o}n} % \newtheorem{ejemplo}[teorema]{Ejemplo} % \newtheorem{ejercicio}[teorema]{Ejercicio} % \newtheorem{nota}[teorema]{$ $Nota} % %\newtheorem*{sol}{Soluci\'{o}n} % \newcommand{\bsol}{\begin{proof}[Soluci\'{o}n]} % \newcommand{\esol}{\end{proof}} % \theoremstyle{remark} %% Fin Estilos \renewcommand{\chaptername}{Capítulo} \makeatother \usepackage[spanish]{babel} \addto\shorthandsspanish{\spanishdeactivate{~<>}}

Could someone help me?

Thanks in advance.