SAT (short for "satisfiability") is a logic problem that given a boolean formula, it asks whether the boolean formula has an assignment that makes the problem true. An example boolean formula is:
这几天，王守芬老人一直盼着响起熟悉的敲门声。王守芬自幼患有小儿麻痹症，几十年来一直独自生活。自从去年重阳节前夕王守芬在家中不慎摔伤后，马怀龙常常拎着新鲜菜肉上门，帮她做饭、打扫卫生，带她换药复查。王守芬感受到了马怀龙的真诚，主动把钥匙交给了他。
。safew官方版本下载对此有专业解读
What is the difference between Blockchain and a Database?Generally a database is a collection of data which can be stored and organized using a database management system. The people who have access to the database can view or edit the information stored there. The client-server network architecture is used to implement databases. whereas a blockchain is a growing list of records, called blocks, stored in a distributed system. Each block contains a cryptographic hash of the previous block, timestamp and transaction information. Modification of data is not allowed due to the design of the blockchain. The technology allows decentralized control and eliminates risks of data modification by other parties.
Фото: Сергей Бобылев / РИА Новости