Changes between Initial Version and Version 1 of Ticket #20973, comment 15


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Timestamp:
07/10/16 18:46:09 (3 years ago)
Author:
andrew.mathas
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  • Ticket #20973, comment 15

    initial v1  
    1111Another direction for relatively easy generalisation is `B_oo` etc.
    1212
    13 I have a related question concerning `cartan_matrix`, and possibly `dynkin_diagram`. I was surprised that matrices indexed by `Z` and `N` are not implemented in sage and, similarly, that graphs with infinite vertex sets are not supported. It would be very easy to implement a fake Cartan matrix, say `C`, that given two integers make `C[i,j]`, or `C[i][j]`, return the corresponding entry of the Cartan matrix. Is some one able to tell me what functionality such a matrix would need in order to be useful to the root system code? Similarly, implementing a fake Dynkin diagram class would be straightforward as long as I knew what methods I have to implement.
     13I have a related question concerning `cartan_matrix`, and possibly `dynkin_diagram`. I was surprised that matrices indexed by `Z` and `N` are not implemented in sage and, similarly, that graphs with infinite vertex sets are not supported. It would be very easy to implement a fake Cartan matrix, say `C`, that given two integers makes `C[i,j]`, or `C[i][j]`, return the corresponding entry of the Cartan matrix. Is some one able to tell me what functionality such a matrix would need in order to be useful to the root system code? Similarly, implementing a fake Dynkin diagram class would be straightforward as long as I knew what methods I have to implement.