Given phrases that describe the relationship between two words/phrases as options, extract the word/phrase pair and the corresponding lexical relationship between them from the input text. The output format should be "relation1: word1, word2; relation2: word3, word4". Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Glencore sees itself as the natural operator of the Rio assets and the Swiss company's chief executive Ivan Glasenberg has been a long-time rival of Davis.

Answer: chief_executive_officer: Glencore, Ivan Glasenberg; owned_by: Glencore, Ivan Glasenberg; owner_of: Ivan Glasenberg, Glencore