rectangle corner symbol

Stream: general

[Huỳnh Trần Khanh]

what does this "rectangle corner" symbol mean? I mean Γ

in the lean-type-theory pdf (https://github.com/digama0/lean-type-theory/releases/tag/v1.0) I see a lot of that symbol and I have no idea what that is... and that symbol seems to be p common elsewhere too whenever type theory is discussed...

example: https://photos.app.goo.gl/YEhns3KTupxG1twQA

[David Wärn]

Capital Gamma. It's a variable representing a context