what network is the channel which started prior to 1979-04-02 on?
Entity Entity Entity Entity Entity
m.02wlv6g m.0ncl8zk m.02bv5k m.03cf611 m.02q8kf9
YLE British Broadcasting Corporation CTV Two Pay TV National Television Company of Ukraine
class class literal
tv.tv_network broadcast.tv_channel 1979-04-02^^http://www.w3.org/2001/XMLSchema#date
tv.tv_network broadcast.tv_channel type.datetime
TV Network TV Channel 1979-04-02
none none <
tv.tv_network.channels broadcast.tv_channel.from
Channels From
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX : <http://rdf.freebase.com/ns/> 
SELECT (?x0 AS ?value) WHERE {
SELECT DISTINCT ?x0  WHERE { 
?x0 :type.object.type :tv.tv_network . 
?x1 :type.object.type :broadcast.tv_channel . 
FILTER (?x2 < "1979-04-02-08:00"^^<http://www.w3.org/2001/XMLSchema#date>)
?x0 :tv.tv_network.channels ?x1 . 
?x1 :broadcast.tv_channel.from ?x2 . 
FILTER ( ?x0 != ?x1 && ?x0 != ?x2 && ?x1 != ?x2  )
}
}
(AND tv.tv_network (JOIN tv.tv_network.channels (lt broadcast.tv_channel.from 1979-04-02^^http://www.w3.org/2001/XMLSchema#date)))