MakePairwiseDisjoint - Maple Help
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RegularChains[ConstructibleSetTools]

  

MakePairwiseDisjoint

  

make the defining regular systems in a constructible set pairwise disjoint

 

Calling Sequence

Parameters

Description

Examples

Calling Sequence

MakePairwiseDisjoint(cs, R)

Parameters

cs

-

constructible set

R

-

polynomial ring

Description

• 

The command MakePairwiseDisjoint(cs, R) returns a constructible set cs1 such that cs1 and cs are equal and the regular systems representing cs1 are pairwise disjoint.

• 

Generally, in a constructible set, there is some redundancy among its components defined by regular systems. By default, functions on constructible sets do not remove redundancy because such a computation is expensive.

• 

This command is part of the RegularChains[ConstructibleSetTools] package, so it can be used in the form MakePairwiseDisjoint(..) only after executing the command with(RegularChains[ConstructibleSetTools]).  However, it can always be accessed through the long form of the command by using RegularChains[ConstructibleSetTools][MakePairwiseDisjoint](..).

Examples

> 

with⁡RegularChains:

> 

with⁡ConstructibleSetTools:

First, define the polynomial ring.

> 

R≔PolynomialRing⁡x,y,a,b,c,d,e

R≔polynomial_ring

(1)

Consider the following almost general linear equations. They are not completely general, since their constant term, namely e, is the same.

> 

F≔a⁢x+b⁢y−e

F≔a⁢x+b⁢y−e

(2)
> 

G≔c⁢x+d⁢y−e

G≔c⁢x+d⁢y−e

(3)

After projecting the variety defined by F and G into the parameter space given by the last 5 variables, you can see when such general linear equations have solutions after specializing the last 5 variables.

> 

cs≔Projection⁡F,G,5,R

cs≔constructible_set

(4)
> 

lrs≔RepresentingRegularSystems⁡cs,R

lrs≔regular_system,regular_system,regular_system,regular_system,regular_system,regular_system,regular_system,regular_system,regular_system

(5)
> 

Info⁡cs,R

,c,d⁢a−b⁢c,a−c,b−d,c,c,d,a,d⁢a−b⁢c,e,d,c,a,b−d,c,d,a,c,e,1,b,d,e,1,c,d,e,a,a,b,c,d,e,1

(6)
> 

nops⁡lrs

9

(7)

There are 9 regular systems defining the image cs of the projection. To remove common parts of these regular systems, use MakePairwiseDisjoint.

> 

cs_mpd≔MakePairwiseDisjoint⁡cs,R

cs_mpd≔constructible_set

(8)
> 

lcs_mpd≔RepresentingRegularSystems⁡cs_mpd,R

lcs_mpd≔regular_system,regular_system,regular_system,regular_system,regular_system,regular_system,regular_system,regular_system,regular_system

(9)
> 

nops⁡lcs_mpd

9

(10)

Now, there are 10 components.

> 

Info⁡cs_mpd,R

a,b,c,d,e,1,c,d,e,a,b,b,d,e,a−c,a,c,e,b−d,d⁢a−b⁢c,e,d,c,b−d,a,b−d,c,d,c,d,a,a−c,b−d,c,,c,d⁢a−b⁢c

(11)

Notice that some components have split during the redundancy removal.

See Also

ConstructibleSet

ConstructibleSetTools

GeneralConstruct

Projection

RefiningPartition

RegularChains