The symbol + is used as infix notation for the Ext-algebra addition. The elements $x$ and $y$ must have the same weight and sign.
i1 : L = lieAlgebra{a,b,c}/{a b,b c}
o1 = L
o1 : LieAlgebra
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i2 : E = extAlgebra(3,L) o2 = E o2 : ExtAlgebra |
i3 : basis(2,E)
o3 = {ext_3, ext_4}
o3 : List
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i4 : ext_4+2 ext_3 o4 = 2ext_3 + ext_4 o4 : E |