deletions | additions       diff --git a/Social_costs_socially_optimal_level__.md b/Social_costs_socially_optimal_level__.md  index 9ed993e..dcc00b7 100644  --- a/Social_costs_socially_optimal_level__.md  +++ b/Social_costs_socially_optimal_level__.md 
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Now we're building a ladder on the iteration of the graph about carbon tax, which kind of reminds me of a 2-D version of a double helix but that might be too meta. It uses 2 dollar increments.   Just did some performance art about water markets but I was thirsty so it might have just been more about maslow's hierarchy of needs than teaching practice. https://en.wikipedia.org/wiki/Maslow%27s_hierarchy_of_needs#/media/File:MaslowsHierarchyOfNeeds.svg