In the early stage, we conducted data collection on the recidivism rate of released prisoners. The data shows that the reciprocity rate was higher than people expected. In some developed countries that we know well, the recidivism rate of prisoners within one year after they were released from prison was nearly 50%-70%. So what causes such a high crime rate? Through the integration of data, it is found that this is related to population, criminal standard setting, government, etc., and it is not caused by a single cause.

Twenty years ago, Norway reformed the method of imprisoning prisoners and moved away from a punitive "lock-up" approach, which sharply cut reoffending rates.

"OK, and now put your big toes together and put your bum behind you!" calls the enthusiastic yoga instructor in English to the 20 or so participants who are shuffling into a child's pose on rubber mats spread out on the grass in the faint early morning sunshine.

"Can you feel the stretch?" she gently asks a heavily tattooed man as she settles his ruffled T-shirt and smoothes his wide back with her hand. "It's OK, yeah?"

This kind of scene can happen in a gym or health resort in any city in the world. But here is actually the Harden Prison with the strongest security measures in Norway. These students might be murderers, rapists, or drug dealers. But now, they are practicing yoga with the guards in the prison, listening carefully and following the instructions of the teacher.

In the 1980s, there was a completely hard management measures prison in Norway. It was a masculine, macho culture with a focus on guarding and security. And the recidivism rate was around 60-70%.

But in the early 1990s, the ethos of the Norwegian Correctional Service underwent a rigorous series of reforms to focus less on what Hoidal terms "revenge" and much more on rehabilitation. Prisoners, who had previously spent most of their day locked up, were offered daily training and educational programmes and the role of the prison guards was completely overhauled.

Guards are no longer guards, but prison managers. Of course, they have to make sure that the criminals serve their full sentences, but at the same time they have to help the criminals to re-behave. Prison managers are models for criminals, helping them and educating them. Since the implementation of this reform, the recidivism rate of Norwegian criminals two years after being released from prison has fallen to only 20% after two years and about 25% after five years. So obviously this reform works!

Norway's practice of prison reform has also provided other countries with great reference. What is the point of sending someone to prison - retribution or rehabilitation? This issue is worth pondering for every country. No matter what method is adopted, it is ultimately necessary to reduce the rate of recidivism, achieve national security and build a harmonious society.