Opened 8 years ago

Closed 8 years ago

## #712 closed bug (fixed)

# example where std( stdI,J ) is not reduced with 'Dp' ordering and 'redSB' option

Reported by: | Owned by: | hannes | |
---|---|---|---|

Priority: | major | Milestone: | 4-1-0 and higher |

Component: | dontKnow | Version: | 4-0-2 |

Keywords: | not reduced standard basis | Cc: |

### Description

failing example:

LIB("primdec.lib"); ring rng = (67),(x,y,z),Dp; short = 0 ; option() ; system("random", 1327212338); ideal I = x^2-9*z,-9*x*y+x-10; ideal J = -6*x*z-10; ideal gI = std(I); ideal IJ = I+J; ideal gIJ = std(IJ); ideal gI_J = std(gI,J); ASSUME(0, 0== size( std(reduce (I,gI ) )) ); ASSUME(0, 0== size( std(reduce (IJ,gIJ ) )) ); ASSUME(0, 0== size( std(reduce (IJ,gI_J ) )) ); ASSUME(0, 0== size( std(reduce (gI_J, gIJ) )) ); ASSUME(0, idealsEqual(gI_J,gIJ )); ASSUME(0, idealsEqual(gIJ, gI_J)); size(gI_J) == size(gIJ) ; // =0 ! gI_J; gIJ;

output

> gI_J; gI_J[1]=z^2+25*x gI_J[2]=y*z-28*x-15*z gI_J[3]=x*z+24 gI_J[4]=x*y-15*x+16 gI_J[5]=x^2-9*z > gIJ; gIJ[1]=y-23*z-15 gIJ[2]=z^2+25*x gIJ[3]=x*z+24 gIJ[4]=x^2-9*z

### Change History (4)

### comment:1 Changed 8 years ago by

### comment:2 Changed 8 years ago by

Reports are assumed to be minimal: but here we had to remove ca 50 % filling

I kept the additional lines to show that the problem does not occur earlier, i.e.

- reduce (I, gI ), reduce (IJ, gIJ ) , reduce (IJ, gI_J ) and reduce (gI_J, gIJ) are ok
- gI_J and gIJ are equal

I'm sorry for the inconvenience in case the additional information was not useful.

### comment:4 Changed 8 years ago by

Resolution: | → fixed |
---|---|

Status: | new → closed |

fixed with ede2ad82162be63d3b994284c909b4cf23aaefbe

std(SB,I) does not allow crit3 because of the (wrong) order of reductions (some were in the SB computation) Solution: disable crit3 optimization: if size(I)*4 > 3*size(SB), use std(SB+I)

**Note:**See TracTickets for help on using tickets.

Reports are assumed to be minimal: but here we had to remove ca 50 % filling (21 -> 11 lines, 500 -> 200 characters). This is really asking for a new solution type "will not consider" or so. Please keep in mind that test cases are not suitable as bug reports and vice versa.