2022-02-08 18:08:14 +0200 received badge ● Supporter (source) 2022-02-08 18:08:12 +0200 commented answer How to construct a matrix space ? Thank you for your answer ! By chance, do you know how can I "reverse" .lift() ? When I create a matrix and try to check 2022-02-08 18:05:44 +0200 marked best answer How to construct a matrix space ? I know we can create a matrix space using "MatrixSpace" but I am looking to create a specific space. I tried : M = MatrixSpace(ZZ,4) B = M.basis() sub = [B[0,0],B[1,3],B[2,2],B[3,1]] SubM = M.submodule(sub) SubM.basis()  The program show me : Finite family {0: B[0], 1: B[1], 2: B[2], 3: B[3]} And when I take a random element of SubM( with SubM.random_element()), it tells me it isn't in M. I thought the problem came from my generator so I tried with : sub = [matrix(4,4,{(0,0):1}),matrix(4,4,{(1,3):1}),matrix(4,4,{(2,2):1}),matrix(4,4,{(3,1):1})] But I have the same result. Do you know what I am doing wrong ? I also need to do a XOR between matrix space, do you think it is possible ? How ? Thanks you for your time :D 2022-02-08 18:05:44 +0200 received badge ● Scholar (source) 2022-02-08 18:05:40 +0200 commented question How to construct a matrix space ? it is not really explained but I guess that it is a matrix space which have as element the xor of elements of 2 matrix s 2022-02-08 00:04:30 +0200 received badge ● Student (source) 2022-02-07 18:18:47 +0200 received badge ● Organizer (source) 2022-02-07 18:18:27 +0200 received badge ● Editor (source) 2022-02-07 18:18:27 +0200 edited question How to construct a matrix space ? How to construct a matrix space ? I know we can create a matrix space using "MatrixSpace" but I am looking to create a s 2022-02-07 18:10:42 +0200 asked a question How to construct a matrix space ? How to construct a matrix space ? I know we can create a matrix space using "MatrixSpace" but I am looking to create a s