IBM conceded Tuesday its artificial intelligence-powered Project Debater lost a competition to a human debate champion but said the experience was an important milestone in efforts to get computers to master human language. In the first live, public debate before a large, in-person and online audience, the declared winner was Harish Natarajan, who holds the record for most debate competition victories, IBM said in a blog post. In the San Francisco debate on Monday, Project Debater and Natarajan were given 15 minutes to prepare for the debate on the merits of subsidizing preschools. The IBM program argued for subsidies, calling it an important tool for helping the poorest members of society; Natarajan spoke against the idea, saying the subsidy fails to address the root causes of poverty and is a "politically motivated giveaway" to middle-class families. The winner of the event was determined by the debater's ability to change the minds of the audience.