Utilize the input text as a context reference, choose the right relationship between Syriza and Alexis Tsipras from the options. 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.

?Equity markets largely in the red... coming down off yesterday's heady reaction to news of a Greek deal, as Alexis Tsipras returns to a revolution within his Syriza party," said Augustin Eden, research analyst at trading firm Accendo Markets.

Answer: chairperson