Answering to myself but maybe somebody is interested ;) Based on my experiments query should be rewritten to encapsulate first order logic operations within one type brackets. query "my query" i: Item( ( x == "A" && q > 0) || ( x == "B" && q > 1 ) ) // ---- Lets forget about this part ;) // $x: Ref( name=="Exp" ) and // Item( x == "A", quantity > 0 ) from $x.items end I still can not find a way to point to items directly inserted into working memory or referenced as property ( Set of Items ) of other type - at the same time. So far I am using rule to contribute to some temporary fact and then retrieving and querying this fact. Not my preferable solution but works :) tk. On Mon, Aug 18, 2008 at 5:15 PM, Tomasz Krzywicki <tkrzywicki(a)gmail.com&gt; wrote: