A graduate level question in complex analysis

In summary, the conversation discusses the proof that if two entire functions, f and g, satisfy the condition that the absolute value of f(z) is less than or equal to the absolute value of g(z) for all z in the complex plane, then f can be written as a constant multiple of g. The speaker mentions using Liouville's theorem and the fact that f/g is bounded and analytic except at the zeros of g. They also note that if a zero of g is also a zero of f, its multiplicity in g is less than or equal to its multiplicity in f. However, the speaker gets stuck and requests help in proving that f/g is also analytic at the zeros of g, so that Liouville
  • #1
vijigeeths
4
0
If f and g are two entire functions such that mod(f(z)) <= mod(g(z)) for all z in C, prove that f=cg for some complex constant c.
 
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  • #2
I tried to prove this by applying Liouville's theorem to f/g.
it is clear that f/g is bounded.
and f/g is analytic except at the zeros of g.
if z1 is a zero of g its a zero of f also.
and if multiplicity of z1 as a zero of g will be less than or equal to multiplicity of z1 as a zero of f.
i got stuck here.
pls help me to prove f/g is analytic at zeros of g also.
so that by Liouville's theorem f/g will be a constant.
 

FAQ: A graduate level question in complex analysis

What is complex analysis?

Complex analysis is a branch of mathematics that deals with the study of functions of complex numbers. It involves the application of calculus and algebra to analyze and manipulate functions of complex variables.

What is the difference between real analysis and complex analysis?

Real analysis deals with functions of real numbers, while complex analysis deals with functions of complex numbers. Complex analysis also involves the study of complex-valued functions, such as the complex exponential, which have no analogues in real analysis.

What are some real-world applications of complex analysis?

Complex analysis has many applications in physics, engineering, and economics. In physics, it is used to study wave phenomena, such as sound and light. In engineering, it is used in the design of electronic circuits and signal processing. In economics, it is used in the study of stock market trends and financial data.

What are some key concepts in complex analysis?

Some key concepts in complex analysis include analytic functions, Cauchy-Riemann equations, complex integration, and the Cauchy integral theorem. These concepts are used to study the behavior of complex-valued functions and to solve problems in various fields.

What is the significance of studying complex analysis at a graduate level?

Studying complex analysis at a graduate level allows for a deeper understanding of the subject and its applications. It also prepares students for more advanced topics in mathematics and other fields, such as mathematical physics and engineering. Additionally, graduate-level courses in complex analysis often involve research and the development of new techniques, contributing to the advancement of the field.

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