Def as @ bs == Case of as; nil  bs ; a.as'  [a / (as' @ bs)]  (recursive)

is mentioned by

Def [e, e'] == filter(ev.es-ble{i:l}(es;e;ev);before(e') @ [e'])	[es-interval]
Def before(e) == if first(e) nil else before(pred(e)) @ [pred(e)] fi Def (recursive)	[es-before]

In prior sections: list 1 mb list 1 mb list 2 mb event system 1

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