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D.5.5.22 constructblwup
Procedure from library resbinomial.lib (see resbinomial_lib).
- Usage:
- constructblwup(blwhist,n,chy,flag);
blwhist, flag lists, n integer, chy ideal
- Return:
- the ideal defining the map K[W] --> K[Wi],
which gives the composition map of all the blowing up leading to this chart
- Note:
- NECESSARY START WITH COLUMNS
Example:
| | LIB "resbinomial.lib";
ring r = 0,(x(1..3)),dp;
list flag=identifyvar();
ideal chy=maxideal(1);
ideal J=x(1)^4*x(2)^2, x(1)^2+x(3)^3;
list L=Eresol(J); // 7 charts
// history of the blow ups at the 7-th chart, center {x(1)=x(3)=0} every time
L[1][7][8]; // blow ups at x(3)-th, x(1)-th and x(1)-th charts
==> [1]:
==> 0,3,0,0
==> [2]:
==> 0,0,0,0
==> [3]:
==> 0,0,1,1
constructblwup(L[1][7][8],3,chy,flag);
==> _[1]=x(1)^3*x(3)
==> _[2]=x(2)
==> _[3]=x(1)^2*x(3)
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