Evaluating a symbolic expression for a Graph

asked 2013-02-14 07:50:33 -0500

patronics gravatar image

updated 2013-02-14 07:50:51 -0500

I'm able to do this:

sage: f = function('radius', nargs=1, evalf_func=Graph.radius)
sage: f(graphs.HouseGraph())

But not this:

sage: var('G')
sage: expr = f(G)
sage: expr.subs(G=graphs.HouseGraph())
TypeError: no canonical coercion from <class 'sage.graphs.graph.Graph'> to Symbolic Ring

What am I missing? Is it not possible to use symbolic expressions like this?

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