Hitachi Go Problems
The Hitachi Go Problems is a weekly (biweekly from April 2018) series of life and death problems by Minoru Harada, a Japanese amateur 8 dan. Each week, two new problems will be posted, one "elementary" and one "intermediate", and the solutions to the previous week's problems will be revealed. Note that his problems are generally challenging and tricky, his typical "elementary" problems far exceed the difficulty of the beginner exercises here.
- https://www.hitachi.co.jp/Sp/tsumego/past/index-e.html 2,000+ problems are amassed as of 2018. The last added problems date February 2020.... Harada passed away in July 2021.
Here are a few discussions of Go problems.
- Hitachi Number 7
- Hitachi Number 9
- Hitachi Number 17
- Hitachi Number 121
- Hitachi Number 314
- Hitachi Number 703 (was shown on the SL Frontpage in the 1st week of November 2009)
- Hitachi Number 830
- Hitachi Number 840
- Hitachi Number 1163
- zinger: Harada's problems are the best I have found on the web - always very realistic game positions. Beware the difficulty labels, however: "elementary" can be tricky, and "intermediate" can be quite hard, at least for me.
- unkx80: I would say that his "elementary" problems often verge into the intermediate/advanced territory. But it is one of the best problem collections.