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Comments on Is there a stable/consistent extension of wheel theory to alephs?

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Is there a stable/consistent extension of wheel theory to alephs?

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In wheel theory (MathSE) (see also Wikipedia here and nLab here), $0/0$ is more tractable than usual. There is a unary version of division, $/a$, which is involutive: $//a = a$, and $0/0$ is used as an absorbing element generally. So the theory goes on to allow for working with division by zero to a greater extent than usual.

Now for transfinite cardinals $\aleph_{\alpha}$, division is pretty much not defined. Even self-subtraction is indeterminate in that e.g. $\aleph_0 - \aleph_0$ might cover a situation in which a set of length $\omega$ was subtracted from, say, $\omega + \omega$, leaving countably many elements behind, so that the result of the cardinal subtraction is again $\aleph_0$. Or one might reduce a countable set so as to leave behind 1000 elements, etc. More generally, as $\aleph_0 + n = \aleph_0$, it is possible to have self-subtraction of an aleph leave any n behind, etc.

Similarly, then, and akin also to self-division of zero, $\frac{\aleph_0}{\aleph_0} = X$ can take any value in $[1, \aleph_0]$. (But dividing an aleph by itself and getting 0 is not granted.)

So, would it be possible to expand upon wheel theory to introduce $\aleph_0/\aleph_0$ as a sort of "top element" antipodal to $0/0$ as a bottom element? And then to have $/\aleph_0$, etc. as "cardinal infinitesimals"? (I'm trying to see if we can use infinite cardinals instead of infinite surreals or infinite hypernumbers in the Robinsonian sense, as the base for infinitesimals. Having looked over Jech's book on the axiom of choice, I was also minded to consider non-aleph infinite cardinals $A$ such that $1/A$ is more tractable, but getting to use the alephs for this purpose is my dream...)

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Any commutative semiring with a chosen multiplicative submonoid can be extended to a wheel of fractions. Cardinal addition and multiplication form a commutative semiring (glossing over the set/proper class distinction), so we can easily talk about the wheel of cardinal fractions with respect to the submonoid of multiplication on \(\mathbb{N}_{>0}\). Formally, the elements of this wheel are equivalence classes of pairs of cardinals \(\kappa : \mu\) under this equivalence relation: \[\kappa_1 : \mu_1 \sim_{\mathbb{N}^\times_{>0}} \kappa_2 : \mu_2 \iff \exists n_1, n_2 \in \mathbb{N}_{>0} \text{ such that } n_1\kappa_1 = n_2 \kappa_2 \wedge n_1\mu_1 = n_2\mu_2 .\]

But as usual, we can use the cardinal \(\kappa\) to refer to the class of \(\kappa : 1\) when there is no confusion.

The reciprocal of \(\aleph_0\), then, is the class of \(1 : \aleph_0\), and we can identify \(\aleph_0/\aleph_0\) as the class containing the fraction product \(\aleph_0\cdot 1 : 1 \cdot \aleph_0 = \aleph_0 : \aleph_0\). What else is equivalent to this pair? Exactly the pairs \(\kappa : \mu\) such that there are non-zero naturals \(n_1, n_2\) satisfying \(n_1 \aleph_0 = \aleph_0 = n_2\kappa = n_2\mu\). Clearly, as \(n_1\) and \(n_2\) are finite and non-zero, their specific values don't matter and \(\kappa = \mu = \aleph_0\). So as requested, we have a value \(\aleph_0/\aleph_0\) that stands apart. In fact, in this wheel, every infinite cardinal \(\kappa\) induces a value \(\kappa/\kappa\) that is distinct from \(0/0\), \(1\), and any other \(\kappa'/\kappa'\).

With respect to the suitability of \(/\aleph_0\) as an infinitesimal, we may wish to define a partial order on our wheel of cardinal fractions. Say that \(\kappa_1 : \mu_1 < \kappa_2 : \mu_2\) iff \(\kappa_1\mu_2 < \kappa_2\mu_1\). This partial order on pairs extends consistently to the wheel of fractions, because the equivalence relation \(\sim_{\mathbb{N}^\times_{>0}}\) adds or removes the same positive finite factors to both sides of the inequality when replacing one pair with another in its equivalence class. Then it follows that \(0 < /\aleph_0 < /n\) for every \(n \in \mathbb{N}_{>0}\):

  • \(0 < /\aleph_0\) because \(0 \cdot \aleph_0 = 0 < 1 \cdot 1 = 1\)
  • \(/\aleph_0 < /n\) because \(1\cdot n = n < 1 \cdot \aleph_0 = \aleph_0\)

With this partial order, we can make some statements about \(\aleph_0/\aleph_0\). While \(0/0\) is incomparable with any other value, we can place \(\aleph_0/\aleph_0\) strictly between 0 and \(\aleph_1\), matching your observation about the range of values \(\aleph_0/\aleph_0\) could take using an intuitive interpretation of cardinal division. Further up the ladder, for any pair of infinite cardinals \(\kappa_1 < \kappa_2\), we have that \(0 < \kappa_1/\kappa_1 < \kappa_2\), but \(\kappa_1/\kappa_1\) is incomparable with any cardinal between (inclusive) 1 and \(\kappa_1\) and with \(\kappa_2/\kappa_2\).

To help demonstrate the structure of this wheel a little bit more fully, I've printed up some operation tables for addition, multiplication, and ordering for some of the simplest cardinal fractions, per the above definitions.

Click to show/hide operation tables \[ \begin{array}{c|c*{15}c} + & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & 0 & /\aleph_1 & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & /\aleph_0 & \tfrac{\aleph_0}{\aleph_0} & 1 & \aleph_0 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \hline \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ 0 & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & 0 & /\aleph_1 & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & /\aleph_0 & \tfrac{\aleph_0}{\aleph_0} & 1 & \aleph_0 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ /\aleph_1 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & /\aleph_1 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0}\\ /\aleph_0 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & /\aleph_0 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ 1 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & 1 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & 2 & \aleph_0 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \aleph_0 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & \aleph_0 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \aleph_0 & \aleph_0 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \aleph_1 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \aleph_1 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0}\\ /0 & \tfrac{\aleph_1}{0} & \tfrac{\aleph_0}{0} & /0 & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & /0 & /0 & \tfrac{\aleph_0}{0} & /0 & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0}\\ \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0}\\ \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0}\\ \end{array} \]\[ \begin{array}{c|c*{15}c} \times & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & 0 & /\aleph_1 & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & /\aleph_0 & \tfrac{\aleph_0}{\aleph_0} & 1 & \aleph_0 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \hline \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0}\\ \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0}\\ 0 & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & 0 & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & 0 & 0 & \tfrac{0}{\aleph_0} & 0 & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0}\\ /\aleph_1 & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & /\aleph_1 & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & /\aleph_1 & \tfrac{\aleph_0}{\aleph_1} & /\aleph_1 & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_1}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0}\\ /\aleph_0 & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & /\aleph_1 & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & /\aleph_0 & \tfrac{\aleph_0}{\aleph_0} & /\aleph_0 & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_0}{\aleph_0} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ 1 & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & 0 & /\aleph_1 & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & /\aleph_0 & \tfrac{\aleph_0}{\aleph_0} & 1 & \aleph_0 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \aleph_0 & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & 0 & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_0}{\aleph_0} & \tfrac{\aleph_0}{\aleph_0} & \aleph_0 & \aleph_0 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_1}{\aleph_0} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & \tfrac{0}{\aleph_0} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0}\\ \aleph_1 & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & 0 & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & \tfrac{\aleph_1}{\aleph_0} & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \aleph_1 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0}\\ /0 & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0} & /0 & \tfrac{\aleph_0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \tfrac{\aleph_1}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{0}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0} & \tfrac{\aleph_1}{0}\\ \end{array} \]\[ \begin{array}{c|c*{15}c} \overset{^?}{\smash{<}} & \tfrac{0}{\aleph_1} & \tfrac{0}{\aleph_0} & 0 & /\aleph_1 & \tfrac{\aleph_0}{\aleph_1} & \tfrac{\aleph_1}{\aleph_1} & /\aleph_0 & \tfrac{\aleph_0}{\aleph_0} & 1 & \aleph_0 & \tfrac{\aleph_1}{\aleph_0} & \aleph_1 & \tfrac{0}{0} & /0 & \tfrac{\aleph_0}{0} & \tfrac{\aleph_1}{0}\\ \hline \tfrac{0}{\aleph_1} & = & \parallel & \parallel & < & < & < & < & < & < & < & < & < & \parallel & < & < & <\\ \tfrac{0}{\aleph_0} & \parallel & = & \parallel & < & < & < & < & < & < & < & < & < & \parallel & < & < & <\\ 0 & \parallel & \parallel & = & < & < & < & < & < & < & < & < & < & \parallel & < & < & <\\ /\aleph_1 & > & > & > & = & \parallel & \parallel & < & < & < & < & < & < & \parallel & < & < & <\\ \tfrac{\aleph_0}{\aleph_1} & > & > & > & \parallel & = & \parallel & < & < & < & < & < & < & \parallel & < & < & <\\ \tfrac{\aleph_1}{\aleph_1} & > & > & > & \parallel & \parallel & = & \parallel & \parallel & \parallel & \parallel & \parallel & \parallel & \parallel & < & < & <\\ /\aleph_0 & > & > & > & > & > & \parallel & = & \parallel & < & < & < & < & \parallel & < & < & <\\ \tfrac{\aleph_0}{\aleph_0} & > & > & > & > & > & \parallel & \parallel & = & \parallel & \parallel & < & < & \parallel & < & < & <\\ 1 & > & > & > & > & > & \parallel & > & \parallel & = & < & < & < & \parallel & < & < & <\\ \aleph_0 & > & > & > & > & > & \parallel & > & \parallel & > & = & < & < & \parallel & < & < & <\\ \tfrac{\aleph_1}{\aleph_0} & > & > & > & > & > & \parallel & > & > & > & > & = & \parallel & \parallel & < & < & <\\ \aleph_1 & > & > & > & > & > & \parallel & > & > & > & > & \parallel & = & \parallel & < & < & <\\ \tfrac{0}{0} & \parallel & \parallel & \parallel & \parallel & \parallel & \parallel & \parallel & \parallel & \parallel & \parallel & \parallel & \parallel & = & \parallel & \parallel & \parallel\\ /0 & > & > & > & > & > & > & > & > & > & > & > & > & \parallel & = & \parallel & \parallel\\ \tfrac{\aleph_0}{0} & > & > & > & > & > & > & > & > & > & > & > & > & \parallel & \parallel & = & \parallel\\ \tfrac{\aleph_1}{0} & > & > & > & > & > & > & > & > & > & > & > & > & \parallel & \parallel & \parallel & =\\ \end{array} \]

I hope you do something interesting with these!

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Works for me (7 comments)
Works for me
Ripheus24‭ wrote 7 months ago

This is what I was hoping for, and more. Thank you so much!

Ripheus24‭ wrote 7 months ago

r~~‭ now my next step is trying to see about inserting $/\aleph_0$ in the basic slope formula $\frac{2x\epsilon + \epsilon^2}{\epsilon}$ for infinitesimal $\epsilon$. I'm looking to see if this justifies the classical "practice of neglect" for consolidating the formula as 2x. Let's see... okay, this'll take a while to write out, I'll get back to the community after I've run some numbers.

Ripheus24‭ wrote 7 months ago · edited 7 months ago

So I came up with a bunch of alternative moments here. For example, we could write the formula like $//\aleph_0(2x/\aleph_0 + /\aleph_0^2)$ (I think, not 100% sure though). Also, assume that we start with $x = \frac{0}{0}$ itself but with $\epsilon = 0$, then at the "end" we have $2\frac{0}{0}$, and given what Euler said about using 0/0 in relation to "any number", it's like having 2x, except that at the level of x generally, the formula/function works in multiple ways as we go between using normal values for x and abnormal ones, and as we vary the $\epsilon$ term to boot.

Ripheus24‭ wrote 7 months ago · edited 7 months ago

r~~‭ I saw at the end of Carlström's 2001 paper that wheel theory "has $\sqrt[n]{m}^{p/q} = \sqrt[q \times n]{m^p}$. In particular, $x^{1/0}$ and $x^{0/0}$ is defined in this way." Now does this eventually allow us to use e.g. $\aleph_0/0$ as an exponent, etc.? I would assume so, and then that these kinds of items would allow for some nifty evaluations. But I still haven't gotten a perfectly "clean" moment of infinitesimal neglect (I can reduce that one slope formula to $2x$ but at the cost of further reducing it to 0/0).

r~~‭ wrote 7 months ago · edited 7 months ago

I don't suspect any of this is likely to be directly useful in a nonstandard-analysis-like framework, since one property you want in nonstandard analysis is to be able to distinguish between \(\epsilon\) and \(\epsilon^2\) terms, and \(/\aleph_0^2 = /\aleph_0\). (This is unavoidable in any wheel that embeds transfinite cardinal arithmetic, because \(\aleph_0^2 = \aleph_0\).)

Ripheus24‭ wrote 7 months ago · edited 7 months ago

r~~‭ not necessarily helpful as an aid in theorizing in terms of infinitesimal analysis, at least not in a well-explored direction, but something occurred to me in that if $0/\aleph_0$ is not equal to 0, it's not equal to 0/1, 0/2, 0/3, etc., but that might allow the abstract introduction of another kind of transfinite cardinal $\lambda$ such that $0/\lambda = 0/n^{> 0} = 0$. This would then also be determinately such that $\lambda - \lambda = 0$ and $\lambda/\lambda = 1$, I think. Not commensurate with the alephs, or not comparable, something in some direction along those lines... And not "ratioed" to the amorphic cardinals either, etc. (Btw, would there be any "socio-historical basis" for referring to wheels involving alephs as "aleph-ophanim," after the category of angels who were visualized as "wheels within wheels"?)

Ripheus24‭ wrote 7 months ago · edited 7 months ago

We'd also have the following inequation/equation string:

$0/0 \neq 0/1 = 0/2 = ... = 0/n = \frac{0}{n+1} = ... \neq \frac{0}{\aleph_0} \neq \frac{0}{\aleph_1} \neq ...$

I don't know if that has much value, and whether all its value is aesthetic and subjective for me. But I thought it was an aesthetic item of contemplation.

Addendum. Something odd: I would have assumed that $0/1 = 0/2$ "just like that" but, and maybe I'm using the alephs naively to say so, but so $(0/1)^{\aleph_0} \neq (0/2)^{\aleph_0}$, it seems, since in the former case the denominator is stuck at 1 but in the latter case it goes to $\beth_1$?