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BoijSoederberg :: matrix(BettiTally,ZZ,ZZ)

matrix(BettiTally,ZZ,ZZ) -- Betti diagram to matrix

Synopsis

Description

If either lowDegree or highDegree is not given, then they are inferred from the Betti diagram itself. The result matrix has highDegree-lowDegree+1 rows, corresponding to these (slanted) degrees.
B = pureBettiDiagram {0,1,4,7}
matrix B
matrix(B,-2)
matrix(B,-2,5)
This function is essentially the inverse of mat2betti.
R = ZZ/101[a..e];
I = ideal borel monomialIdeal"abc,ad3,e4";
B = betti res I
C = matrix B
B == mat2betti C
If the lowest degree of the matrix is not 0, then this information must be supplied in order to obtain the inverse operation.
B = pureBettiDiagram {-2,0,1,2,5}
C = matrix B
mat2betti(C,-2)

Caveat

Currently, the error messages are not that illuminating. The [lowDegree, highDegree], if given, must be as large as the actual degree range

See also