Ya esta:
<script type="application/javascript">
function selectOnlyOne(current_clicked) {
//alert(current_clicked);
var a = document.getElementById(current_clicked).value;
alert(a);
if(a=='ac-1'){
document.getElementById('ac-3').checked=false;
}else if(a=='ac-3'){
document.getElementById('ac-1').checked=false;
}
}
</script>