# How to create in Sage system of equations using elements from boolean field?

I want to create a field on 8 elements, and then, using this elements make a System of equations like:

nb = 8
varl = [c+ str(p) for c in 'xy' for p in range (nb)]
B = BooleanPolynomialRing(names = varl)

f1 = x1 + x7*x2

f2 = x4*x6*x8 + x7


and then....

But in this case Sage give me an error NameError: name 'x1' is not defined

And in this case:

f1 = x[3] + x[1]*x[2]
f2 = x[4]*x[6]*x[2] + x[7]


error: TypeError: 'sage.symbolic.expression.Expression' object does not support indexing

Is there any way to create them in Sage?

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When you write f1 = x1 + x7*x2, you assume that the Python name x1 points to the boolean indeterminate x1, but there is nothing in your code that assign the Python name x1 to something.

You can to that with:

sage: B.inject_variables()
Defining x0, x1, x2, x3, x4, x5, x6, x7, y0, y1, y2, y3, y4, y5, y6, y7

more

Thank you, it helps:)

( 2019-05-30 14:45:43 +0200 )edit

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Last updated: May 30 '19