TY - JOUR
T1 - Fractal oracle numbers
AU - Ratsaby , Joel
N1 - Publisher Copyright:
© 2024 World Scientific Publishing Company.
PY - 2024
Y1 - 2024
N2 - Consider orbits (z,) of the fractal iterator f(z):= z2 + , that start at initial points z K(m) where is the set of all rational complex numbers (their real and imaginary parts are rational) and K(m) consists of all such z whose complexity does not exceed some complexity parameter value m (the complexity of z is defined as the number of bits that suffice to describe the real and imaginary parts of z in lowest form). The set K(m) is a bounded-complexity approximation of the filled Julia set K. We present a new perspective on fractals based on an analogy with Chaitin's algorithmic information theory, where a rational complex number z is the analog of a program p, an iterator f is analogous to a universal Turing machine U which executes program p, and an unbounded orbit (z,) is analogous to an execution of a program p on U that halts. We define a real number ϒ which resembles Chaitin's ω number, where, instead of being based on all programs p whose execution on U halts, it is based on all rational complex numbers z whose orbits under f are unbounded. Hence, similar to Chaitin's ω number, ϒ acts as a theoretical limit or a "fractal oracle number"that provides an arbitrarily accurate complexity-based approximation of the filled Julia set K. We present a procedure that, when given m and , it uses ϒ to generate K(m). Several numerical examples of sets that estimate K(m) are presented.
AB - Consider orbits (z,) of the fractal iterator f(z):= z2 + , that start at initial points z K(m) where is the set of all rational complex numbers (their real and imaginary parts are rational) and K(m) consists of all such z whose complexity does not exceed some complexity parameter value m (the complexity of z is defined as the number of bits that suffice to describe the real and imaginary parts of z in lowest form). The set K(m) is a bounded-complexity approximation of the filled Julia set K. We present a new perspective on fractals based on an analogy with Chaitin's algorithmic information theory, where a rational complex number z is the analog of a program p, an iterator f is analogous to a universal Turing machine U which executes program p, and an unbounded orbit (z,) is analogous to an execution of a program p on U that halts. We define a real number ϒ which resembles Chaitin's ω number, where, instead of being based on all programs p whose execution on U halts, it is based on all rational complex numbers z whose orbits under f are unbounded. Hence, similar to Chaitin's ω number, ϒ acts as a theoretical limit or a "fractal oracle number"that provides an arbitrarily accurate complexity-based approximation of the filled Julia set K. We present a procedure that, when given m and , it uses ϒ to generate K(m). Several numerical examples of sets that estimate K(m) are presented.
KW - Chaitin's ω
KW - Complex Dynamics
KW - Computation Theory
KW - Fractal Sets
UR - http://www.scopus.com/inward/record.url?scp=85183619836&partnerID=8YFLogxK
U2 - 10.1142/S0218348X24500294
DO - 10.1142/S0218348X24500294
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AN - SCOPUS:85183619836
SN - 0218-348X
VL - 32
JO - Fractals
JF - Fractals
IS - 1
M1 - 2450029
ER -