['tricorder', 'pick', 'sign', 'EmptyParameter', 'EmptyParameter'] ['they', 'follow', 'footprint', 'EmptyParameter', 'EmptyParameter']
['tricorder', 'chew-39.2-1', "Synset('information.n.02')", 'EmptyParameter', 'EmptyParameter'] ['<PRP>', 'comprehend-87.2', "Synset('extent.n.02')", 'EmptyParameter', 'EmptyParameter']
Their tricorders don't pick up any life signs, so they follow the footprints instead.
<PRP> tricorder don't pick up any Synset('record.n.01') signs, so <PRP> follow the Synset('extent.n.02') instead.