Fixed() placement #321

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1. brandmaier commented on Oct 6, 2026

   

   brandmaier

   on Oct 6, 2026

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   @aaronpeikert, can you please comment on this if you find time?
2. aaronpeikert commented on Oct 7, 2026

   

   aaronpeikert

   on Oct 7, 2026

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   This is indeed something to wrap your head around but actually intended behavior.
   Fundamentally, this is the difference between Arrows and Edges.
   Edges behave exactly like you'd expect:

   using StenoGraphs, StructuralEquationModels
   
   a = Node(:a)
   b = Node(:b)
   
   UndirectedEdge(fixed(1)*b, a) == UndirectedEdge(a, fixed(1)*b) == @StenoGraph(b ↔ a*fixed(1))[1]

   Arrows behave that way (i.e. ignore modifiers on the left side) because they are chainable. Otherwise this would be ambiguous:

   graph = @StenoGraph begin
       a ↔ b*fixed(1) ↔ c
   end

   More fundamentally, that already a ↔ b ↔ c is ambiguous (and why) is explained here:

   https://aaronpeikert.github.io/StenoGraphs.jl/dev/man/arrows/