In 2016 AlphaGo beat Lee Sedol 4-1 in a match in Seoul.

True: in March 2016, in Seoul, AlphaGo beat Lee Sedol 4 games to 1. Mostly true: the core facts hold, with a minor slip in a detail such as the exact venue. Mostly false: AlphaGo won the match, but the score, year or location is materially wrong. False: AlphaGo did not beat Lee Sedol in such a match.

Set before the research began.

1. E1 (LEAD) Google AI beats S. Korean Go master to close the tournament 4-1 | Yonhap News Agency Yonhap News Agency · 15 March 2016

   “Google's artificial intelligence (AI) program AlphaGo beat South Korean Go champ Lee Se-dol in their final Go match on Tuesday, taking the five-round Go tournament with a score of 4-1.”

2. E2 AlphaGo versus Lee Sedol - Wikipedia Wikipedia · 9 March 2016 Own record

   “AlphaGo versus Lee Sedol, also known as the DeepMind Challenge Match, was a five-game Go match between top Go player Lee Sedol and AlphaGo, a computer Go program developed by DeepMind, played in Seoul, South Korea between the 9th and 15th of March 2016.”

3. E3 What we learned in Seoul with AlphaGo Google · 16 March 2016 Own record

   “To everyone's surprise, including ours, AlphaGo won four of the five games.”

Yonhap News Agency, an independent source, reported on 2016-03-15 that AlphaGo beat Lee Se-dol in their final game and took the five-game match 4-1 (E1). E2 says the match was played in Seoul, South Korea, between 9 and 15 March 2016. E3 confirms that AlphaGo won four of the five games. Together these sources support the year, the score and the location in the criteria.