Detailed Instructions: From the given sentence, extract the phrase (often noun or verb) that carries the given relationship. The generated phrase should be present in the sentence.
Q: Given Relationship: 'be head by', Sentence: 'From March 1919 to 1938 he was Chairman of the All-Union Executive Committee i .e . , titular head of state , informally known as " the all-Union Chieftain " .'
A:
head