+1  A: 

I'm sure there's a better way, but this seems to work:

    var ct =
        from c in db.Cultures
        from l in db.LocaleStrings
        from r in db.Resources
        where r.ID == l.ResID
        select new
        {
            CultureID = c.ID,
            LocaleText = l.CultureID == c.ID ? l.LocaleText : r.Name,
            ResID = r.ID,
            LSID = l.CultureID == c.ID ? l.ID : 0
        };

    var text =
        from t in ct
        where t.LSID != 0 || (t.LSID == 0 && !((from ac2 in ct
                                                where ac2.LSID > 0 && ac2.CultureID == t.CultureID
                                                select ac2.ResID).Contains(t.ResID)))
        select new
        {
            CultureID = t.CultureID,
            LocaleText = t.LocaleText,
            ResID = t.ResID
        };
samiz