function valide_form (){
	if (document.form.category.value == ""){
		alert ("You forgot to select a category");
		document.form.category.focus(); 
		return false;
	}
	if (document.form.title.value == ""){
		alert ("You forgot to write your title");
		document.form.title.focus(); 
		return false;
	}else if(document.form.title.value.length > 250){
		alert ("Your title must not exceed 250 characters");
		document.form.title.focus(); 
		return false;	
	}
	if (document.form.authors.value == ""){
		alert ("You forgot to write yours authors");
		document.form.authors.focus(); 
		return false;
	}else if(document.form.authors.value.length > 250){
		alert ("Your authors must not exceed 250 characters");
		document.form.authors.focus(); 
		return false;	
	}
	if (document.form.institutions.value == ""){
		alert ("You forgot to write yours institutions");
		document.form.institutions.focus(); 
		return false;
	}else if(document.form.institutions.value.length > 250){
		alert ("Your institutions must not exceed 250 characters");
		document.form.institutions.focus(); 
		return false;	
	}
	if (document.form.first_corresponding.value == ""){
		alert ("You forgot to write your corresponding author's first name");
		document.form.first_corresponding.focus(); 
		return false;
	}
	if (document.form.last_corresponding.value == ""){
		alert ("You forgot to write your corresponding author's last name");
		document.form.last_corresponding.focus(); 
		return false;
	}
	if (document.form.mail_corresponding.value == ""){
		alert ("You forgot to write your corresponding author's e-mail");
		document.form.mail_corresponding.focus(); 
		return false;
	}else{
		var arobase = document.form.mail_corresponding.value.indexOf("@"); var point = document.form.mail_corresponding.value.lastIndexOf(".");
		if((arobase < 3)||(point + 2 > document.form.mail_corresponding.value.length)||(point < arobase+3)){
			alert("Your corresponding author's e-mail is not valid !"); 
			document.form.mail_corresponding.value=""; 
			document.form.mail_corresponding.focus(); 
			return false
		}
	}
	if (document.form.mail_corresponding_2.value == ""){
		alert ("You forgot to write your corresponding author's confirm e-mail");
		document.form.mail_corresponding_2.focus(); 
		return false;
	}else{
		var arobase = document.form.mail_corresponding_2.value.indexOf("@"); var point = document.form.mail_corresponding_2.value.lastIndexOf(".");
		if((arobase < 3)||(point + 2 > document.form.mail_corresponding_2.value.length)||(point < arobase+3)){
			alert("Your corresponding author's confirm e-mail is not valid !"); 
			document.form.mail_corresponding_2.value=""; 
			document.form.mail_corresponding_2.focus(); 
			return false
		}
	}
	if (document.form.mail_corresponding.value!=document.form.mail_corresponding_2.value){
		alert("Your corresponding author's e-mail and your corresponding author's confirm e-mail are not identical!"); 
		document.form.mail_corresponding_2.value=""; 
		document.form.mail_corresponding_2.focus(); 
		return false
	}
	if (document.form.first_presenting.value == ""){
		alert ("You forgot to write your presenting author's first name");
		document.form.first_presenting.focus(); 
		return false;
	}
	if (document.form.last_presenting.value == ""){
		alert ("You forgot to write your presenting author's last name");
		document.form.last_presenting.focus(); 
		return false;
	}
	if (document.form.mail_presenting.value == ""){
		alert ("You forgot to write your presenting author's e-mail");
		document.form.mail_presenting.focus(); 
		return false;
	}else{
		var arobase = document.form.mail_presenting.value.indexOf("@"); var point = document.form.mail_presenting.value.lastIndexOf(".");
		if((arobase < 3)||(point + 2 > document.form.mail_presenting.value.length)||(point < arobase+3)){
			alert("Your presenting author's e-mail is not valid !"); 
			document.form.mail_presenting.value=""; 
			document.form.mail_presenting.focus(); 
			return false
		}
	}
	if (document.form.mail_presenting_2.value == ""){
		alert ("You forgot to write your presenting author's confirm e-mail");
		document.form.mail_presenting_2.focus(); 
		return false;
	}else{
		var arobase = document.form.mail_presenting_2.value.indexOf("@"); var point = document.form.mail_presenting_2.value.lastIndexOf(".");
		if((arobase < 3)||(point + 2 > document.form.mail_presenting_2.value.length)||(point < arobase+3)){
			alert("Your presenting author's confirm e-mail is not valid !"); 
			document.form.mail_presenting_2.value=""; 
			document.form.mail_presenting_2.focus();
			return false
		}
	}
	if (document.form.mail_presenting.value!=document.form.mail_presenting_2.value){
		alert("Your presenting author's e-mail and your presenting author's confirm e-mail are not identical!"); 
		document.form.mail_presenting_2.value=""; 
		document.form.mail_presenting_2.focus();
		return false
	}
	if (document.form.text.value == ""){
		alert ("You forgot to write your text");
		document.form.text.focus(); 
		return false;
	}else if(document.form.text.value.length > 2000){
		alert ("Your text must not exceed 2000 characters");
		document.form.text.focus(); 
		return false;	
	}
	if (document.form.disclosure.value == ""){
		alert ("You forgot to write your disclosure statements");
		document.form.disclosure.focus(); 
		return false;
	}else if(document.form.disclosure.value.length > 250){
		alert ("Your disclosure statements must not exceed 2000 characters");
		document.form.disclosure.focus(); 
		return false;	
	}
	
	return true;
}