spielwiese
Last change
on this file since 85d15b1 was
a62b2c,
checked in by Hans Schönemann <hannes@…>, 23 years ago
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*hannes: new libs
git-svn-id: file:///usr/local/Singular/svn/trunk@5030 2c84dea3-7e68-4137-9b89-c4e89433aadc
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1.1 KB
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1 | LIB "primdec.lib"; |
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2 | ring r = 0,(x,y,z,t,w),dp; |
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3 | ideal i= |
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4 | x2+2y2+2z2+2t2-x, |
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5 | 2xy+2yz+2zt-y, |
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6 | y2+2xz+2yt-z, |
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7 | x+2y+2z+2t-1; |
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8 | primdecGTZ(i); |
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9 | // We consider now the ideal J of the base space of the |
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10 | // miniversal deformation of the cone over the rational |
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11 | // normal curve computed in section *11* and compute |
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12 | // its primary decomposition. |
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13 | ring R = 0,(A,B,C,D),dp; |
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14 | ideal J = CD, BD+D2, AD; |
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15 | primdecGTZ(J); |
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16 | // We see that there are two components which are both |
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17 | // prime, even linear subspaces, one 3-dimensional, |
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18 | // the other 1-dimensional |
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19 | // (This is Pinkhams example and was the first found |
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20 | // surface singularity with two components of |
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21 | // different dimensions) |
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22 | // |
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23 | // Let us now produce an embedded component in the last |
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24 | // example, compute the minimal associated primes and |
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25 | // the radical. We use the Characteristic set methods |
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26 | // from prim_dec.lib. |
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27 | J = intersect(J,maxideal(3)); |
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28 | primdecSY(J,1); //shows that the maximal ideal is |
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29 | //embedded (takes a few seconds) |
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30 | minAssChar(J,1); |
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31 | radical(J); |
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32 | LIB "tst.lib";tst_status(1);$ |
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