function all()
		{
			var obj = document.getElementById("carteles");
			obj.style.display = "none";
			var obj = document.getElementById("presentaciones");
			obj.style.display = "none";
			var obj = document.getElementById("platicas");
			obj.style.display = "none";
		}

function ocultar($cja)
		{
			var obj = document.getElementById($cja);
			obj.style.display = "none";
		}

function mostrar($cja) {
	var obj = document.getElementById($cja);
	obj.style.display = "block";
}

function all_ca()
		{
			var obj = document.getElementById("poster");
			obj.style.display = "none";
			var obj = document.getElementById("presentaciones");
			obj.style.display = "none";
			var obj = document.getElementById("platicas");
			obj.style.display = "none";
		}

function all_pl()
		{
			var obj = document.getElementById("poster");
			obj.style.display = "none";
			var obj = document.getElementById("presentaciones");
			obj.style.display = "none";
			var obj = document.getElementById("carteles");
			obj.style.display = "none";
		}

function all_pr()
		{
			var obj = document.getElementById("poster");
			obj.style.display = "none";
			var obj = document.getElementById("carteles");
			obj.style.display = "none";
			var obj = document.getElementById("platicas");
			obj.style.display = "none";
		}