original: stallman pioneered the concept of copyleft and is the main author of several copyleft licenses including the gnu general public license , the most widely used free software license .
simplifications: stallman pioneered the copyleft concept and holds the license to the most popular free software license , the gnu general public license . stallman contributed much to copyleft licenses such as the widely used gnu general public license . stallman , the father of copyleft and several copyleft licenses the gnu general public license stallman pioneered the concept of copyright and is the main author of several copyright licenses including the gnu -lrb- general public license -rrb- , the most widely used free software license . stallman was the first to use the concept of copyleft and is the main author of several copyleft licenses including the gnu general public license , the most widely used free software license . the gnu general public license , a widely used free software license , was created by stallman . stallman pioneered the concept of copyleft and is the main author of several copyleft licenses including the gnu general public license , the most widely used free software license . stallman pioneered the concept of copyleft and is the main author of several copyleft licenses including the gnu general public license , the most widely used free software license .