I have this code to build a dynamic Query with Examine:

var criteria = searchProvider.CreateSearchCriteria(IndexType.Content);
IBooleanOperation query = ????? ;   

if (!string.IsNullOrEmpty(q))
    query = query.And().GroupedOr(new[] { "title", "bodyText", "abstract" }, new[] { q });
if (!string.IsNullOrEmpty(Request["type"]))
    query = query.And().Field("type", Request["type"].Escape());
if (!string.IsNullOrEmpty(Request["tag"]))
    query = query.And().Field("tags", Request["tag"].Escape());

var results = searchProvider.Search(query.Compile());

But I'm not sure how go get from criteria to Iboolean operator where all clauses are optional. (well there should be at least one, but it can be any one)

I could create each permutation but that would be messy.