“GM May I?”

Some players start to feel hamstrung if they feel that every action they take is subject to the GM's whim. A carefully written game can anticipate this and make it clear that the things that the players can do, the players can do. In other words, if a character's main thing is hitting stuff with an axe, that kind of thing needs to be spelled out in the rules with enough clarity that the player knows how it will work and can play that part of the game without GM "permission." Speaking of which, it's also important that the rules present themselves in such a way that the GM isn't providing "permission," he's adjudicating. It's a fine difference, but an important one. When a player says, "Can my character jump across the pit?" she's not asking, "May my character jump across the pit?" She's asking, "Does it seem possible that my character could jump across the pit?" Players are in control of their characters. They don't need GM permission.
From Cook, Monte. “Logic in RPGs.” Monte Cook’s Blog. 5 June 2012. Web. 29 Aug. 2012.
http://www.goodreads.com/author_blog_posts/2549114-logic-in-rpgs