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In spite of over two decades of intense research , illumination and pose invariance remain prohibitively challenging aspects of face recognition for most practical applications .
 conjunction: illumination, pose invariance; part of: illumination, face recognition; part of: pose invariance, face recognition
Given a phrase that describes the relationship between two words, extract the words and the lexical relationship between them. The output format should be "relation1: word1, word2; relation2: word3, word4". 
Option: conjunction, feature of, hyponym of, used for, part of, compare, evaluate for 
Text: {0} 
Answer:
 conjunction: illumination, pose invariance; part of: illumination, face recognition; part of: pose invariance, face recognition