Filtered algebra
Associated graded algebra
Let 𝐴 be a filtered algebra over 𝕂 with filtration (𝐹𝑖𝐴)∞𝑖=1.
The associated graded algebra 𝐺∙𝐴 is the direct sum of vector spaces ⨁∞𝑖=1𝐺𝑖𝐴 where 𝐺0𝐴 =𝐹0𝐴 and 𝐺𝑖+1𝐴 =𝐹𝑖+1𝐴/𝐹𝑖𝐴1
with multiplication given by #m/def/ralg
(𝑥+𝐹𝑖𝐴)⋅(𝑦+𝐹𝑗𝐴)=𝑥⋅𝑦+𝐹𝑖+𝑗𝐴
for 𝑥 ∈𝐹𝑖+1𝐴 and 𝑦 ∈𝐹𝑗+1𝐴.
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