5450
He returned to Germany in November 1918 upon an invitation from Fritz Kater to join him in Berlin to re-build the  Free Association of German Trade Unions  (  FVdG  ) .
 alternate names: Free Association of German Trade Unions, FVdG
Given options, please tell me the relationships of all the listed entity pairs.Output format is "relation1: word1, word2; relation2: word3, word4". 
Option: cities of residence, top members employees, members, alternate names, origin, state or provinces of residence, title of person, spouse, city of headquarters, NA, founded by, state or province of headquarters, employee of, countries of residence, country of birth, founded, subsidiaries, country of headquarters 
Text: {0} 
 Entity Pairs:  Free Association of German Trade Unions, FVdG 
Answer:
 alternate names: Free Association of German Trade Unions, FVdG