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ExtElement -- the class of all Ext-algebra elements


This type represents elements in Ext-algebras. Each object of type ExtAlgebra is itself a type E, and homogeneous elements in E belong also to the type ExtElement, which is the parent of E. Internally an element of type ExtElement is of type BasicList consisting of two basic lists, the first is a list of coefficients and the second is a list of indices for the generators occurring in the element.

i1 : L = lieAlgebra{a,b}/{a a b,b b a}

o1 = L

o1 : LieAlgebra
i2 : E = extAlgebra(5,L)

o2 = E

o2 : ExtAlgebra
i3 : x = 4 ext_2 - ext_3

o3 = 4ext_2 - ext_3

o3 : E
i4 : x#0

o4 = BasicList{4, -1}

o4 : BasicList
i5 : x#1

o5 = BasicList{2, 3}

o5 : BasicList

See also

Functions and methods returning an object of class ExtElement :

Methods that use an object of class ExtElement :

For the programmer

The object ExtElement is a type, with ancestor classes BasicList < Thing.