open problems survey  Printable Version + Tetration Forum (https://math.eretrandre.org/tetrationforum) + Forum: Tetration and Related Topics (https://math.eretrandre.org/tetrationforum/forumdisplay.php?fid=1) + Forum: Mathematical and General Discussion (https://math.eretrandre.org/tetrationforum/forumdisplay.php?fid=3) + Thread: open problems survey (/showthread.php?tid=162) Pages:
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open problems survey  bo198214  05/17/2008 This thread is for mathematicians looking for challenges. Rules for posting in this thread: a) One open problem/conjecture per post (except very closely related problems) b) Put a meaningful title together with a succeeding problem id into the post subject. c) Every problem shall be stated clearly and basicly, if necessary by giving an introduction before and linking to relevant resources. d) Avoid problems like: "find the best algorithm for ...", "investigate more on ...", "is there a connection between ...", etc. Make effort to culminate the problem in a yes/no question or conjecture. e) If you found a proof or have a comment then dont post it here but open a new thread containing the string "TPID n" where n is replaced by the problem number. This way comments and proofs for a problem can by found by searching the forum for that string, while the problems thread stays clean and readable. eigenvalues of Carleman matrix for b^x, TPID 1  bo198214  05/17/2008 Conjecture Let be the Bell/Carleman matrix of , , truncated to rows and columns. There is an enumeration of the eigenvalues of such that where is the lower real fixed point of . Explanation This is a key question for deciding whether the diagonalization/matrix power method is independent of its development point. A more general question would be under which circumstances the eigenvalues of the Carleman matrix converge to the powers of an attracting fixed point. It seems they dont do for which has an attracting fixed point at and a repelling fixed point at . Also the behaviour of the eigenvalues for seems unclear. However there is only one real repelling fixed point in this case. Notes is the derivative of at : Exponential Factorial, TPID 2  andydude  05/26/2008 Conjecture (Part 1): The exponential factorial (EF) is uniquely determined by the assumptions:
Conjecture (Part 2): This is contingent on part 1, and if it is uniquely determined by these conditions, then , the EulerMacheroni constant. Discussion: Starting with the definition of the exponential factorial , and differentiating we get and evaluating at one, we get . So by finding EF(0) we are really finding the first coefficient of the power series expansion of EF (about x=1). A numerical approximation of the power series of EF using only these first principles will give a value of . Aside from the numerical approximations, if we assume that EF is invertible at one, then that means that EF'(1) is nonzero, which means that EF(0) is nonzero. Here is the first few real solutions. There seems to always be exactly 2 real solutions for every approximation, but the number of complex solutions increases with the approximation number. Code: M = Number of coefficients These coefficients correspond to the functions: Below I have attached of some graphs made with these approximations. Notice that values of the function for are required to be complex. eigenvalues of Carleman matrix for (x+s)^ps, TPID 3  bo198214  06/29/2008 Conjecture Let be the Carleman matrix of (truncated to N rows and columns), , real. Then the set of eigenvalues of converges to the set for in the sense that there exist an enumeration of the Eigenvalues of such that for each . Discussion This is about the function shifted by . The fixed point 0 is a singularity for (for nonnatural ), so has to be developed at the different point . In the particular case we have the fixed point at 0 and the first derivative is . So the Carleman matrix is triangular and we can solve it exactly, getting . The conjecture is again about the independence of the matrix function method with respect to the development point. can even be developed at the fixed point 0 in the particular case . However in this case except and regular iteration can not be applied, which makes sense as can for most t not be developed at 0. Existence of bounded b^z TPID 4  bo198214  10/08/2008 We know that the recurrence for (1) (2) has as the only entire solution that is bounded on the strip . The image of under is an annulus for and so bounded. We know that for complex the function is not bounded on (the image is kinda infinite spiral) for any . The question remains whether Conjecture There is no entire solution that satisfies (1) and (2) and is bounded on for complex . sqrt(2) tetrational is completely discontinuous TPID 5  bo198214  05/01/2009 For a discussion of the topic see http://math.eretrandre.org/tetrationforum/showthread.php?tid=198&pid=2411#pid2411 Conjecture Let . Every real function on that satisfies: is not continuous at any point. Limit of selfsuperroots is e^1/e. TPID 6  andydude  10/07/2009 Conjecture where such that Discussion To evaluate f at real numbers, an extension of tetration is required, but to evaluate f at positive integers, only realvalued exponentiation is needed. Thus the sequence given by the solutions of the equations The conjecture is proven to be true. Search the forum for "TPID 6". A conjecture on bounds. TPID 7  andydude  10/23/2009 Conjecture The following holds for regular tetration: for all and 0 < y < 1. The following holds for intuitive tetration: for all and 0 < y < 1. Discussion This would be interesting in its own right, partly because it is symmetric, but also because it is useful in demonstrating the difference between reciprocal heights and superroots. Another notable aspect of this set of bounds is that it is very extensiondependent. This does not hold for linear tetration. Appended are several graphs of the function for x = 1.001, 1.1, eta, e, 10. The first three (1.001, 1.1, eta) were calculated with regular tetration, and the last two (e, 10) were calculated with intuitive tetration. More discussion of this is here Elementary superfunction of polynomial without real fixed points TPID 8  bo198214  04/25/2010 Is there an elementary real function , such that is a real polynomial of degree at least 2 without real fixed points. Logarithm reciprocal TPID 9  bo198214  07/20/2010 Let the sequence be defined recursively in the following way for : and for Is ? The conjecture is proven to be true. See http://arxiv.org/abs/1008.1409 and also the discussions: Logarithm reciprocal True or false logarithm There is also a resultless (as of this writing) thread in sci.math.research and sci.math called "Logarithm reciprocal". 