Opened 12 years ago

Closed 8 years ago

# classify in classify.lib crashes for T[3,4,4]

Reported by: Owned by: steenpass pfister minor 3-1-4 and higher singular-libs 3-1-3 classify.lib, classify, student project magdaleen@…

### Description

```> option(noloadLib);
> LIB "classify.lib";
> ring r = 0,(x,y,z),ds;
> classify(x3+y4+z4+xyz);
About the singularity :
Milnor number(f)   = 10
Corank(f)          = 3
Determinacy       <= 8
Guessing type via Milnorcode:   T[k,r,s]=T[3,4,4] Q[6k+4]=Q[10]

Computing normal form ...
Arnold step number 54
The singularity
x3+xyz+y4+z4
is R-equivalent to R[p,q] = T[3,p,q].
Milnor number = 10
modality      = 1
? `p` is undefined
? error occurred in or before classify.lib::DecodeNormalFormString line 2756: `r = p;`
? leaving classify.lib::DecodeNormalFormString
skipping text from `;` error at token `)`
? leaving classify.lib::normalform
? leaving classify.lib::classify
. ;
>
```

### comment:1 Changed 12 years ago by steenpass

This seems to be another example for the same bug:

```> option(noloadLib);
> LIB "classify.lib";
> ring r = 0, (x,y,z), ds;
> poly p = x5+y5+z2+xyz;   // This is the case T[5,5,2]
> classify(p);
About the singularity :
Milnor number(f)   = 11
Corank(f)          = 2
Determinacy       <= 9
Guessing type via Milnorcode:   Z[k,12k+6r-1]=Z[1,11] Y[k,r,s]=Y[1,1,1]

Computing normal form ...
I have to apply the splitting lemma. This will take some time....:-)
Arnold step number 16
The singularity
-1/4x2y2+x5+y5
is R-equivalent to Y[1,p,q] = T[2,4+p,4+q].
Milnor number = 11
modality      = 1
? `p` is not defined
? error occurred in or before classify.lib::DecodeNormalFormString line 2756: `r = 4+p;`
? leaving classify.lib::DecodeNormalFormString
skipping text from `;` error at token `)`
? leaving classify.lib::normalform
? leaving classify.lib::classify
.
```

### comment:2 Changed 11 years ago by Oleksandr

Keywords: student project added changed from somebody to pfister

### comment:3 Changed 11 years ago by steenpass

Here are more issues of classify.lib:

```LIB "classify.lib";

ring r2 = 0, (x,y), ds;
classify(x4+x2y2+y4);     // X[9]: gives wrong normal form
classify(x3+x2y2+y7);     // J[k], k > 10: takes too long
classify(x2y2+x5+y8);     // Y[r, s]: crashes
classify((x2+y2)^2+x5);   // Y[r]: crashes

ring r3 = 0, (x,y,z), ds;
map phi = r3, 9x+5y-7z, -9x+y-3z, -7x-2z;
classify(x3+x2z+xz2+y2z);      // P[8]: gives wrong normal form
classify(x3+x2z+y2z+z4);       // P[k], k > 8: gives wrong normal form
classify(x*(x2+yz)+y5+z5);     // R[l, m]: crashes
classify(x*(x2+y2+z2)+y5);     // R[m]: crashes
classify(xyz+x3+y4+z5);        // T[p, q, r]: crashes
classify(x*(y2+z2)+x4+y4);     // T[p, m, m]: crashes
poly q10 = x3+y2z+z4+xz3;
classify(phi(q10));            // Q[10]: doesn't give any type
poly q11 = x3+y2z+xz3+z5;
classify(phi(q11));            // Q[11]: doesn't give any type
poly q12 = x3+y2z+z5+z4x;
classify(phi(q12));            // Q[12]: doesn't give any type
classify(z*(x2+yz)+y4+y3z);    // S[11]: doesn't give any type
classify(z*(x2+yz)+xy3+y5);    // S[12]: doesn't give any type
classify(x*(x2+y2)+z4+xyz2);   // U[12]: claims that this
// "is not in Arnolds list" (sic!)
```

### comment:4 Changed 8 years ago by hannes

Resolution: → fixed new → closed
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