#19551 closed defect (fixed)
Basic failures in projective product morphisms
Reported by:  bhutz  Owned by:  

Priority:  minor  Milestone:  sage6.10 
Component:  algebraic geometry  Keywords:  product projective morphism 
Cc:  bhutz  Merged in:  
Authors:  Tom Salvi, Joseph Eisner  Reviewers:  Ben Hutz 
Report Upstream:  N/A  Work issues:  
Branch:  1ded112 (Commits, GitHub, GitLab)  Commit:  
Dependencies:  Stopgaps: 
Description
The following are simple bugs in projective product morphisms:
PP.<x,y,z,u,v,w>=ProductProjectiveSpaces(QQ,[1,1,1]) HP=End(PP) f=HP([v*x^2,w*y^2,z^2,u^2,v^2,w^2]) Q=PP([0,1,1,1,1,0]) f(Q)
R.<s,t>=PolynomialRing(QQ) Z.<a,b,x,y,z> = ProductProjectiveSpaces([1,2],QQ) P.<u,v,w,s,t,r>=ProductProjectiveSpaces([3,1],QQ) H =Hom(Z,P) f = H([a^2,b^2,a^2,a*b,a*x,b*z])
the following should fail (not multihomogeneous) but passes
Z.<a,b,c,x,y,z> = ProductProjectiveSpaces([1,3],QQ) P.<u,v,w,s,t,r>=ProductProjectiveSpaces([2,2],QQ) H =Hom(Z,P) f = H([a^2,b^2,c^2,x^2,y^2,z^2])
Change History (14)
comment:1 Changed 6 years ago by
comment:2 Changed 6 years ago by
 Branch set to u/tsalvi/ticket/19551
comment:3 Changed 6 years ago by
 Commit set to 2858087c035d7b533419ea04666c810d7ae10d67
 Status changed from new to needs_review
New commits:
2858087  19551: fix failures in projective projects

comment:4 Changed 6 years ago by
 Reviewers set to Ben Hutz
 Status changed from needs_review to needs_work
A couple comments:
 There is a test failure in morphism.py. That test is checking if the map is a nonmorpism, but the map is actually poorly defined. So correct the map to still be a nonmorphism, but a valid map.
 I think we need at least some basic input checking in call, e.g. that the codomain of the point is in the domain of the function, otherwise examples like the following are badly behaved:
PP.<t0,t1,t2,t3,t4>=ProductProjectiveSpaces([2,1],ZZ) Q=PP([1,1,1,2,1]) Z.<a,b,x,y,z> = ProductProjectiveSpaces([1,2],ZZ) H = End(Z) f = H([a^3,b^3+a*b^2,x^2,y^2z^2,z*y]) f(Q)
While we are fixing call, I think you should add a test for the parameter check
as well, such as the following:
PP.<x,y,z,u,v,w,s,t>=ProductProjectiveSpaces(QQ,[3,3]) HP=End(PP) g=HP([4*v*x^2,2*w*y^2,2*v*z^2,2*s*x*y,v^2,w^2,3*s*v,t^2]) P=PP([1,1,2,1,1,0,3,1]) g(P,check=False)
comment:5 Changed 5 years ago by
 Commit changed from 2858087c035d7b533419ea04666c810d7ae10d67 to d705d0196f22cf0313240da6b4e4fec1202659a1
Branch pushed to git repo; I updated commit sha1. New commits:
d705d01  19551: added check and examples

comment:6 Changed 5 years ago by
 Commit changed from d705d0196f22cf0313240da6b4e4fec1202659a1 to 7054db6d8b3a301db65ca77ddbf35d08f3343eb8
Branch pushed to git repo; I updated commit sha1. New commits:
7054db6  Merge branch 'master' into t/19551/ticket/19551

comment:7 Changed 5 years ago by
Still needs some minor work:
should have spaces around the =
sage: PP.<t0,t1,t2,t3,t4>=ProductProjectiveSpaces([2,1], ZZ)
On lines 12, 39, 62, 149, 388 there is terminating white space
In the functions init, call no space around = for check
2 doc test failures
comment:8 Changed 5 years ago by
 Commit changed from 7054db6d8b3a301db65ca77ddbf35d08f3343eb8 to 1ded112bc0f82424e24ec6355d382a5ad64af4f6
Branch pushed to git repo; I updated commit sha1. New commits:
1ded112  19551: fix issues about spacing and doctest

comment:9 Changed 5 years ago by
 Status changed from needs_work to needs_review
comment:10 Changed 5 years ago by
 Status changed from needs_review to positive_review
Still needs some minor work:
should have spaces around the =
sage: PP.<t0,t1,t2,t3,t4>=ProductProjectiveSpaces([2,1], ZZ)
On lines 12, 39, 62, 149, 388 there is terminating white space
In the functions init, call no space around = for check
2 doc test failures
New commits:
1ded112  19551: fix issues about spacing and doctest

comment:11 Changed 5 years ago by
 Branch changed from u/tsalvi/ticket/19551 to 1ded112bc0f82424e24ec6355d382a5ad64af4f6
 Resolution set to fixed
 Status changed from positive_review to closed
comment:12 Changed 5 years ago by
 Commit 1ded112bc0f82424e24ec6355d382a5ad64af4f6 deleted
comment:14 Changed 5 years ago by
Also, just want to make sure that it should be "Tom Salvi" and not "Thomas P. Salvi" as you registered.
Call also needs some basic input checking: