# Symbolic equivalence

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Hi all,

I define ;

sage: x,y,z=var("x y z")
sage: x=y+z
sage: x
y + z
sage: y
y


I want to achieve the following:

sage: y
x-z


any idea how this scenario would be possible ?

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I do not think I understand your question, but note you have sage: bool(y == x-z) that evaluates to True I do not understand what you exactly mean by "I want to achieve ...".

( 2015-04-19 21:49:44 +0100 )edit

What I tried to mean is that when I query for "y" I want to get the corresponding equivalence. I want to construct the equations in such a way that Sage will be aware of this. Bool works but not exactly what I want.

( 2015-04-20 10:06:39 +0100 )edit

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Use an equation to encode the relations between the variables.

You can then solve the equation with respect to the variable of your choice.

An example:

sage: x,y,z = var('x y z')
sage: eq = x==y+z
sage: solve(eq, x)
[x == y + z]
sage: solve(eq, y)
[y == x - z]

more

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