In my TeX document Theorems, Definitions, Lemmas are enumerated in the following way:
Definition 1.1
Lemma 1.1
Theorem 1.1
Definition 1.2
Lemma 1.2
Theorem 1.2
But I would like to have
Definition 1.1
Lemma 1.2
Theorem 1.3
Definition 1.4
Lemma 1.5
Theorem 1.6
How can I obtain this?
Edit. The begin of my document is:
\documentclass[12pt]{article}
\usepackage[T1]{fontenc}
\usepackage[cp1250]{inputenc}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{latexsym}
\usepackage{amsthm}
\theoremstyle{plain}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{corollary}{Corollary}[section]
\newtheorem{lemma}{Lemma}[section]
\newtheorem{observation}{Observation}[section]
\newtheorem{proposition}{Proposition}[section]
\theoremstyle{definition}
\newtheorem{definition}{Definition}[section]
\newtheorem{example}{Example}[section]
Best Answer
Just use the first optional argument, that denotes the counter to share: