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PushForward :: NoPrune

NoPrune -- NoPrune option for pushFwd

Description

This is an optional argument for the pushFwd function. Its default value is false, which means that the presentation of a pushed forward module is pruned by default. If NoPrune is set to true, then the prune calls in pushFwd are turned off.

i1 : R5=QQ[a..e]

o1 = R5

o1 : PolynomialRing
i2 : R6=QQ[a..f]

o2 = R6

o2 : PolynomialRing
i3 : M=coker genericMatrix(R6,a,2,3)

o3 = cokernel | a c e |
              | b d f |

                              2
o3 : R6-module, quotient of R6
i4 : G=map(R6,R5,{a+b+c+d+e+f,b,c,d,e})

o4 = map(R6,R5,{a + b + c + d + e + f, b, c, d, e})

o4 : RingMap R6 <--- R5
i5 : notpruned = pushFwd(G,M,NoPrune => true)

o5 = cokernel {0} | e c 0 a-b-d 0  0          0              0                 |
              {0} | 0 d 0 b+d   de be         bc-ad+bd+cd+d2 0                 |
              {1} | 0 0 c -1    0  -e         0              -de               |
              {1} | 1 0 d 1     -c -a+b+c+d+e c+d            bc-ad+bd+cd+d2+de |

                              4
o5 : R5-module, quotient of R5
i6 : pruned = pushFwd(G,M)

o6 = cokernel | c -de               |
              | d bc-ad+bd+cd+d2+de |

                              2
o6 : R5-module, quotient of R5

Functions with optional argument named NoPrune :

For the programmer

The object NoPrune is a symbol.