I think Cassowary [1] is what you're talking about (particularly section 1.2 where they talk about some modifications to make their system very fast for increme

I think Cassowary [1] is what you're talking about (particularly section 1.2 where they talk about some modifications to make their system very fast for incremental updates). Apple has based their constraint-based layout system, Autolayout [2], on Cassowary. There's also a project that incorporates Cassowary constraints into a CSS-like declarative syntax called GSS [3]. [1] https://www.cs.washington.edu/research/constraints/cassowary/cassowary-tr.pdf https://www.cs.washington.edu/research/constraints/cassowary... [2] https://developer.apple.com/library/ios/documentation/userexperience/conceptual/AutolayoutPG/Introduction/Introduction.html https://developer.apple.com/library/ios/documentation/userex... [3] http://gridstylesheets.org/ http://gridstylesheets.org/