Non-Archimedean Artificial Intelligence – Alpha Theory
Non-Archimedean mathematics enlarges the familiar real number system into a richer numerical universe where infinite and infinitesimal quantities stand side by side with ordinary finite ones. This expansion matters for Artificial Intelligence because the way we represent numbers shapes the way we reason with them. In symbolic and evolutionary AI, for example, it is often useful to speak rigorously about “arbitrarily small” perturbations, “unbounded” resources, or limits of procedures; yet standard real analysis either rules such talk out or buries it under epsilon-delta bookkeeping.
Alpha Theory provides a compact axiomatization of these ideas. It introduces an ordered field $E$ that contains $\mathbb{R}$ and also an infinite element $\alpha$ with infinitesimal inverse $\eta=\alpha^{-1}$. What follows is not merely a list of definitions. Each notion is introduced to solve a concrete problem: how to embed $\mathbb{R}$ into a larger field without losing algebra; how to carry familiar truths (continuity, differentiability) into the new setting; how to interpret $\alpha$ as a “size” (numerosity) and, finally, how to compute with these objects in finite machines via Algorithmic Numbers. The thread that ties the chapter together is simple: extend, transfer, interpret, and compute.
1. Extending the Number System
We begin by demanding that limits of real sequences taken “at $\alpha$” behave exactly like ordinary limits with respect to constants and algebraic operations. This is the hinge that lets us move from $\mathbb{R}$ to a bigger field $E$ without breaking arithmetic.
There exists an ordered field $E \supset \mathbb{R}$ and a function $$\lim_{n \uparrow \alpha} : \mathbb{R}^{\mathbb{N}} \to E$$ such that:
- If $c_r(n)=r$ for all $n\in\mathbb{N}$, then $\lim_{n\uparrow\alpha} c_r(n)=r$.
- If $i(n)=n$ for all $n\in\mathbb{N}$, then $\lim_{n\uparrow\alpha} i(n)=\alpha\notin\mathbb{N}$.
- Limits preserve addition and multiplication: $$ \lim_{n\uparrow\alpha}\varphi(n)+\lim_{n\uparrow\alpha}\psi(n)=\lim_{n\uparrow\alpha}(\varphi(n)+\psi(n)), $$ $$ \lim_{n\uparrow\alpha}\varphi(n)\cdot\lim_{n\uparrow\alpha}\psi(n)=\lim_{n\uparrow\alpha}(\varphi(n)\cdot\psi(n)). $$ Elements $\xi\in E$ are called Euclidean numbers. The element $\alpha$ is infinite, and $\eta:=\alpha^{-1}\in E$ is infinitesimal.
The point of Axiom 1 is twofold. First, it guarantees we have room in $E$ for new magnitudes (infinite and infinitesimal) without sacrificing the algebra of $\mathbb{R}$. Second, it fixes the behavior of the “$\alpha$-limit” so that we can transport sequences from the classical world into the extended one. From here on, expressions like $-\alpha\pi+\eta\alpha$ and $-3+5e^{\eta}$ are perfectly legitimate elements of $E$.
2. Naming the New Magnitudes
Having built $E$, we must say precisely what we mean by infinite, finite, and infinitesimal. These are not metaphors: they are order statements in $E$.
These definitions make $\eta=\alpha^{-1}$ the paradigmatic infinitesimal: $0<\eta<1$, yet $\eta$ is smaller than any positive real. They also allow us to reason algebraically with the new scales exactly as in $\mathbb{R}$; for instance, $$ \alpha(\alpha+2)=\alpha^2+2\alpha, $$ and we have the useful chain $$ 0<\eta=\alpha^{-1}<\alpha^0=1<\alpha^1=\alpha<\alpha+1. $$ At a glance: $\alpha$ dominates finite quantities; $\eta$ is dominated by them.
3. Interpreting $\alpha$ as “Size”: Numerosity
We next give $\alpha$ a concrete combinatorial meaning. Intuitively, $\alpha$ ought to be the “number of naturals.” Numerosity makes that precise.
There exists a function $\mathrm{num}:\mathcal{U}\to E$ such that:
- $\mathrm{num}(A)=|A|$ if $A$ is finite;
- If $A\subset B$ then $\mathrm{num}(A)<\mathrm{num}(B)$;
- $\mathrm{num}(A\cup B)=\mathrm{num}(A)+\mathrm{num}(B)-\mathrm{num}(A\cap B)$;
- $\mathrm{num}(A\times B)=\mathrm{num}(A)\cdot\mathrm{num}(B)$.
Defining $\alpha:=\mathrm{num}(\mathbb{N})$ gives $\alpha$ the role of a bona-fide “count” of the naturals in $E$.
The narrative payoff is substantial: numerosity extends counting in a way that respects subset-monotonicity and product structure. This will later dovetail with algorithmic representations, where sizes and scales matter computationally.
4. Internal Sets and Extending Functions
Axiom 1 embeds sequences; two additional axioms ensure we can carry sets and functions across the bridge.
This says: limits of sets are witnessed by limits of their elements. It is the set-theoretic analogue of linearity of limits and keeps our construction constructive.
Axiom 3 gives us a calculus on $E$: polynomials, exponentials, trigonometric functions, and so on, all lift coherently. For example, combining $\eta=\alpha^{-1}$ with ${}^\ast e$ makes expressions like $-3+5e^{\eta}$ meaningful; expanding rational combinations shows classical algebra at work in $E$, e.g. $$ \frac{-10.0,\alpha^2 + 16.0 + 42.0,\eta^2}{5.0,\alpha^2 + 7.0}
-2.0 + 6.0,\eta^2, $$ so long as we compute with the understanding that $\eta=\alpha^{-1}$ and collect like orders.
5. Transferring Truths: What Survives the Journey?
We now ask: which statements from the first-order language of analysis remain true when transported to $E$? This is the content of the Transfer Principle.
\sigma!\left(\lim_{n\uparrow\alpha}\varphi_1(n),\dots,\lim_{n\uparrow\alpha}\varphi_k(n)\right). $$
The message is reassuring: local analytic facts (continuity, differentiability, algebraic identities) transfer to $E$. Indeed, $$ \alpha(\alpha+2)=\alpha^2+2\alpha $$ is a trivial instance. Likewise, familiar inequalities survive in the expected order (e.g., $0<\eta<1<\alpha<\alpha+1$).
But not everything transfers. Some truths about $\mathbb{R}$ are second-order in nature and thus lie outside the scope of the principle.
Completeness of $\mathbb{R}$ does not transfer to $E$. A vivid counterexample is the monad of zero $$ \mu(0):={x\in E\mid x\approx 0}, $$ the “cloud” of infinitesimals around $0$. It is bounded yet lacks a supremum in $E$, illustrating precisely where the Transfer Principle stops.
6. How Rigid Is $\alpha$? Coherence and Qualified Sets
At this point a natural question arises: Is $E$ unique? Not in general—there are multiple non-isomorphic enlargements of $\mathbb{R}$. Often one writes $E={}^\ast\mathbb{R}$ to stress that we are working in a non-standard extension.
Similarly, simple arithmetical predicates may fail to pin down $\alpha$: it need not be even; it is not guaranteed that $\alpha^n\in {}^\ast\mathbb{N}$ for all $n$; the status of $\sqrt{\alpha}$ as a non-standard integer is model-dependent. To coordinate such properties, we add a combinatorial guardrail:
The axiom forces $\alpha$ to lie in a rich, highly composite family, excluding incoherent combinations (e.g., “$\alpha$ is prime” alongside “$\alpha^2\in {}^\ast\mathbb{N}$”).
7. From Infinite Mathematics to Finite Machines
So far our story has been conceptual. AI systems, however, run on finite hardware. Real numbers such as $1/3$ have infinite expansions; computers therefore work in floating-point arithmetic (IEEE 754), a finite subset of $\mathbb{R}$ augmented with symbols like $\pm\infty$ and NaN. The set of exactly representable numbers is sometimes called an algorithmic field: it obeys many algebraic laws, but not all—associativity, for example, can fail in corner cases: $$ (-2^{127}+2^{127})+1 = 1, \qquad -2^{127}+(2^{127}+1) = 0. $$ These pathologies are more than curiosities. In long training runs or delicate policy updates, they can steer optimization onto different trajectories.
There is a broader trade-off at work. Symbolic arithmetic offers “infinite precision” but slows as expressions grow—each iteration fattens the representation and programs get progressively slower. Fixed-length arithmetic flips the script: operations are standardized (good for CPUs and accelerators), timing is predictable, but noise and overflow become part of the model.
8. Algorithmic Numbers (ANs): A Computable Slice of $E$
To connect the elegance of $E$ with the constraints of machines, we isolate a structured subset of $E$ that is algebraically expressive yet algorithmically tractable.
This form is reminiscent of a Laurent-like expansion in the non-Archimedean scale $\alpha$. We can further normalize every AN into a tidy canonical shape.
Two caveats illuminate the computational stakes. First, ANs are not closed under inversion (e.g., $(\alpha+1)^{-1}$ may leave the class). Second, the pair $(p,m)$ can change under algebraic simplifications, so the length of an AN representation is variable—a latent cost in iterative algorithms.
9. Truncation and BANs: Fixing Length Without Losing the Plot
A practical response is to truncate expansions so that representations remain bounded in size, much like controlling series order in numerical methods.
This leads to a “fixed-budget” subclass of ANs.
BANs strike a balance. They retain the multi-scale expressiveness of $E$ (via $\alpha$ and $\eta$) while guaranteeing a bounded representation size, which is crucial for predictable runtimes, memory footprints, and hardware acceleration. In practice, a BAN behaves like a finite stencil over non-Archimedean scales: enough structure to model infinite/infinitesimal effects; enough discipline to run on silicon.
10. Why This Matters in AI
We can now close the loop. Alpha Theory lets us extend the numeric canvas; the Transfer Principle tells us which truths we can safely carry across; numerosity interprets $\alpha$ as a size; ANs and BANs show how to actually compute in this enlarged universe.
For symbolic AI, infinitesimals formalize defaults, perturbations, and tie-breakers without ad-hoc hacks. For evolutionary and reinforcement learning, infinite scales model asymptotics and limits cleanly, while BAN-style truncations keep learning dynamics compatible with fixed-length hardware arithmetic. And across the board, thinking in $E$ clarifies how rounding, overflow, and representation interact with the logic of our algorithms—making our systems not only more powerful in theory, but also more predictable in practice.