arXiv subjects

Marek Karaś

Publications and source records attributed to Marek Karaś.

6 recordsLinked to original sources

arXiv2021

Dependence of Homogeneous Components of Polynomials with Small Degree of Poisson Bracket

Let F,G in C[x_1,...,x_n] be two polynomials in n variables x_1,...,x_n over the complex numbers field C. In this paper, we prove that if the degree of the Poisson bracket [F,G] is small enough then there are strict constraints for homogeneous components of these polynomials. We also prove that there is a relationship between the homogeneous components of the polynomial F of degrees deg(F)-1 and deg(F)-2 as well some results about divisibility of the homogeneous component of degree deg(F)-1. Moreover we propose, possibly an appropriate, reformulation of the conjecture of Yu regarding the estimation of the Poisson bracket degree of two polynomials.

math.AC↗

arXiv2012

On weighted bidegree of polynomial automorphisms of C^2

Let $F=(F_1,F_2):C^2 ---> C^2 be a polynomial automorphism. It is well know that deg F_1 | deg F_2 or deg F_2 | deg F_1. On the other hand, if (d_1,d_2) \in (N\{0})^2 is such that d_1 | d_2 or d_2 | d_1, then one can construct a polynomial automorphism F=(F_1,F_2) of C^2 with deg F_1=d_1 and deg F_2=d_2. Let us fix w=(w_1,w_2) \in (N\{0})^2 and consider the weighted degree on C[x,y] with wdeg x=w_1$ and wdeg y=w_2. In this note we address the structure of the set {(\wdeg F_1,\wdeg F_2) : (F_1,F_2) is an automorphism of C^2}.

math.AG↗

arXiv2012

Wild multidegrees of the form (d,d_2,d_3) for given d greather than or equal to 3

Let d be any number greather than or equal to 3. We show that the intersection of the set mdeg(Aut(C^3))\ mdeg(Tame(C3)) with {(d_1,d_2,d_3) : d=d_1 =< d_2 =< d_3} has infinitely many elements, where mdeg h = (deg h_1,...,deg h_n) denotes the multidegree of a polynomial mapping h=(h_1,...,h_n):C^n ---> C^n. In other words, we show that there is infiniltely many wild multidegrees of the form (d,d_2,d_3), with fixed d >= 3 and d =< d_2 =< d_3, where a sequences (d_1,...,d_n) is a wild multidegree if there is a polynomial automorphism F of C}^n with mdeg F=(d_1,...,d_n), and there is no tame autmorphim of C^n with the same multidegree.

math.AG↗

arXiv2011

Multidegrees of tame automorphisms of C^n

Let F=(F_1,...,F_n):C^n --> C^n be a polynomial mapping. By the multidegree of the mapping F we mean mdeg F=(deg F_1,...,deg F_n), an element of N^n. The aim of this paper is to study the following problem (especially for n=3): for which sequence (d_1,...,d_n) in N^n there is a tame automorphism F of C^n such that mdeg F=(d_1,...,d_n). In other words we investigate the set mdeg(Tame(C^n)), where Tame(C^n) denotes the group of tame automorphisms of C^n and mdeg denotes the mapping from the set of polynomial endomorphisms of C^n into the set N^n. Since for all permutation s of {1,...,n} we have (d_1,...,d_n) is in mdeg(Tame(C^n)) if and only if (d_s(1),...,d_s(n)) is in mdeg(Tame(C^n)) we may focus on the set mdeg(Tame(C^n)) intersected with {(d_1,...,d_n) : d_1<=...<=d_n}. In the paper, among other things, we give complete description of the sets: mdeg(Tame(C^n)) intersected with {(3,d_2,d_3):3<=d_2<=d_3}}, mdeg(Tame(C^n)) intersected with {(5,d_2,d_3):5<=d_2<=d_3}}, In the examination of the last set the most difficult part is to prove that (5,6,9) is not in mdeg(Tame(C^n)). As a surprising consequence of the method used in proving that (5,6,9) is not in mdeg(Tame(C^n)), we obtain the result saying that the existence of tame automorphism F of C^3 with mdeg F=(37,70,105) implies that two dimensional Jacobian Conjecture is not true. Also, we give the complete description of the following sets: mdeg(Tame(C^n)) intersected with {(p_1,p_2,d_3):3<=p_1<p_2<=d_3}}, where p_1 and p_2 are prime numbers, mdeg(Tame(C^n)) intersected with {(d_1,d_2,d_3):d_1<p_2<=d_3}}, where d_1 and d_2 are odd numbers such that gcd(d_1,d_2)=1. Using description of the last set we show that the set mdeg(Aute(C^n))\mdeg(Tame(C^n)) is infinite.

math.AG↗

arXiv2009

There is no tame automorphism of C^3 with muldidegree (3,4,5)

Let F=(F_1,...,F_n):C^n --> C^n be any polynomial mapping. By multidegree of F, denoted mdeg F, we call the sequence of positive integers (deg F_1,...,F_n). In this paper we addres the following problem: for which sequence (d_1,...,d_n) there is an automorphism or tame automorphism F:C^n --> C^n with mdeg F=(d_1,...,d_n}. We proved, among other things, that there is no tame automorphism F:C^3 --> C^3 with mdeg F=(3,4,5).

math.AG↗

arXiv2009

Tame automorphisms of C^3 with multidegree of the form (p_1,p_2,d_3)

Let d_3 >= p_2 > p_1 >= 3 be integers such that p_1,p_2 are prime numbers. In this paper we show that the sequence (p_1,p_2,d_3) is the multidegree of some tame automorphisms of C^3 if and only if d_3 is in p_1*N+p_2*N, i.e. if and only if d_3 is a linear combination of p_1 and p_2 with coefficients in N.

math.AG↗