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SpectralSequences :: truncate(ChainComplex,ZZ)

truncate(ChainComplex,ZZ) -- compute the hard truncation of a chain complex

Synopsis

Description

Computes the hard trucaton of a chain complex as a specified homological degree.

i1 : B = QQ[a..d];
i2 : C = koszul vars B

      1      4      6      4      1
o2 = B  <-- B  <-- B  <-- B  <-- B
                                  
     0      1      2      3      4

o2 : ChainComplex
i3 : truncate(C,1)

                  4      6      4      1
o3 = image 0 <-- B  <-- B  <-- B  <-- B
                                       
     0           1      2      3      4

o3 : ChainComplex
i4 : truncate(C,-1)

      1      4      6      4
o4 = B  <-- B  <-- B  <-- B  <-- image 0
                                  
     0      1      2      3      4

o4 : ChainComplex
i5 : truncate(C,-10)

o5 = image 0 <-- image 0 <-- image 0 <-- image 0 <-- image 0
                                                      
     0           1           2           3           4

o5 : ChainComplex
i6 : truncate(C,10)

o6 = image 0 <-- image 0 <-- image 0 <-- image 0 <-- image 0
                                                      
     0           1           2           3           4

o6 : ChainComplex

Ways to use this method: