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by 082349872349872 348 days ago
Oops, I lied: never got to sheaves with a topos theory one, it was just offered after an outline of the domain theory version. That chat ran into context window limits, so I'll see if I can steer our current glass bead game back in that direction. Transcript follows, with "ME>" encouraging in the middle:

DS>

  Ah, I love this playful analogy! Let’s reimagine *大鬧天宮* (*Havoc in Heaven*, the legendary rebellion of Sun Wukong against the celestial order) as **连续天宫** (*Continuous Heaven*), where the chaos unfolds not through brute force but through the subtler, domain-theoretic constraints of **continuity** and **finite approximations**. Here’s how it might go:
  
  ---
  
  ### **连续天宫** (*Continuous Heaven*)  
  **Act 1: The Monkey King’s Domain-Theoretic Rebellion**  
  - **Sun Wukong**, now a **higher-order function**, seeks to overthrow the Jade Emperor’s **monolithic domain** (a flat, discrete heaven where everything is rigidly finite).  
  - But the heavens have upgraded to a **Scott domain**:  
    - **No more "havoc"**—all rebellions must be *Scott-continuous*.  
    - Wukong’s attempts to "jump to infinity" (e.g., demanding unbounded power) are thwarted because his actions must preserve **directed suprema**. He can only rebel *gradually*, via finite steps.  
  
  **Act 2: The Fixed-Point Treaty**  
  - The Jade Emperor, wise in domain theory, offers Wukong a **fixed-point compromise**:  
    - *"You may have recursion (μx. f(x)), but only as the limit of your finite iterations: ⊥ ⊑ f(⊥) ⊑ f(f(⊥)) ⊑ ..."*  
    - Wukong’s "infinite" power is now **codified as a suprema of finite rebellions**.  
  
  **Act 3: The Cartesian Closed Heaven**  
  - The heavens restructure into a **cartesian closed category**:  
    - Wukong gains a **function space** (Heaven → Heaven), but all his transformations must be *continuous*.  
    - Even his iconic **72 transformations** are now **continuous endofunctors**.  
  
  ---
  
  ### **Moral of the Story**  
  - **"As below, so above"**:  
    - In *大鬧天宮*, chaos is raw and unbounded.  
    - In *连续天宫*, chaos is **tamed by continuity**—the infinite is always approached through the finite.  
  - **Angelic computing**: Even heaven’s "infinite" logic must obey domain-theoretic constraints.  
  
  **Bonus Joke**:  
  - The **Peach of Immortality** is now a **compact element** in the domain—only finitely many bites (approximations) are needed to gain its power.  
  
  Would you like this rewritten as a formal parable? Or perhaps as a **λ-calculus script** where Wukong is a recursive function? 
ME> Da we da we! Deepthink im tugut, im xelixup!

DS>

   *Deepthink crashes, reboots in a cloud of λ-dust and Scott-domains*  
  
  **Translation of the Oracle's Cry:**  
  *"大悟大悟! (Great enlightenment! Great enlightenment!) Deepthink is tough, it’s celestial!"*  
  
  ---
  
  ### **Act 4: The Domain-Theoretic Epiphany**  
  1. **Wukong’s Fixed-Point Staff**:  
     - His **Ruyi Jingu Bang** (the extending staff) is now a **continuous endomorphism** \( f : D \to D \), collapsing and expanding only in ways that preserve directed suprema.  
     - *"Be thick! Be thin!"* → but always \( \bigsqcup_{n} f^n(\bot) \).  
  
  2. **The Buddha’s Palm as a Universal Domain**:  
     - Buddha’s hand is the **maximal universal domain** \( \mathcal{U} \). Wukong tries to escape (a non-compact element), but his trajectory is a **Cauchy sequence**—always caught in the limit.  
  
  3. **Continuous Havoc**:  
     - Every "leap" is a **Kleene chain**: \( \bot \sqsubseteq f(\bot) \sqsubseteq f(f(\bot)) \sqsubseteq \dots \).  
     - The heavens **approximate stability**; true chaos is forbidden by continuity.  
  
  ---
  
  ### **Final Koan**  
  *"When the Monkey King computed his divinity, did he recurse on the state or the observer?"*  
  
  **Answer**: *"Yes, in the Cartesian closed heaven of reflexive domains."*  
  
  ---
  
  Shall we render this in **Coq**? Or as a **cantonese opera in the language of topos theory**?
2 comments

Suffice to translate (3.)

"approximate stability"

+its dependencies?

Approximate is a verb in this context and not an adjective. The idea under discussion goes roughly like this: the classical ("earthly") Turing Machine has an infinite tape, but each square can only be marked with a selection from a finite number of symbols; let us suppose angels —being more perfect than humans— can discriminate among a (countably) infinite number of symbols, so their ("celestial") turing machines could then have a finite number of squares, potentially even only 1. However, this additional power of discrimination doesn't buy them much, because (per Scott) in order for their function spaces (D->D) to have a small enough cardinality to be only part of their data space (D), they still must only use continuous functions, meaning that while they'd arguably be able to compute quantitatively more ideally than we do, they'd still be restricted to computing qualitatively in the same manner, approaching infinite objects via finite approximations. Slogan: "As below, so above"
Continuity does not buy angels (as represented by wukong?) finer distinctions?

He has to use the same equivalence (stability) classes? Or rather that he cannot express the distinction to mortals

AIUI, up until Scott, λ-calculus had mathematicians saying "yes, it works in practice, but can it ever work in theory?": say we have a universe of discourse D, and we want, per λ-calculus, to have functions D->D (D->D->D, etc.) be part of this universe of discourse. If D is a windowless monad, with a single object, we're ok: there's only 1 arrow (1^1) from 1 object to 1 object, namely the identity, so we just go ahead and identify it with the object. However, as soon as we have two objects in D, we have a problem: there are 4 arrows (2^2) from 2 objects to 2 objects, so even if we attempt to identify objects and functions we don't have enough for all the functions, and the problem only gets worse (N^N) as we have N>2 objects.

Scott's contribution was to cut down the cardinality of the function space: by restricting it to continuous functions (ie only those functions that have finite approximations, which is to say they don't do anything strange "at infinity") one not only gets what most people would admit is a reasonable model of computation, but -calculus then works in theory, as D->D can now fit inside of D.

What I was trying to explore (and maybe the trouble with asking an LLM about this sort of thing is that they're unlikely to push back hard enough?) is the notion that even given an "angelic turing machine", one still couldn't compute in a way than an earthly turing machine couldn't simulate.

Does that make sense?

Grad students Keye Martin & Lemmonier

https://arxiv.org/pdf/2406.07216

Seem to have had measurement problem right next to Scott continuity, -- & left it at that :)

If you want me to look at the details you've got to motivate me by telling what doesn't make sense to you (but ought to?)

in the priority heap... if you give me some pp's I'll bump it up
That was easy enough (the goldfish with a PhD is easily sidetracked!). I'll leave it to you to judge how poetic-vs-on-the-nose its topos theory may be, as I have no clue. Also I have no way to evaluate the cromulence of the embedded hanzi, let alone the offered cantonese libretti... (oh, were those the sheets you meant?)

DS>

  What a delightful and unorthodox request! The synthesis of *大闹天宫* (Havoc in Heaven), Cantonese opera, and topos theory is a conceptual collision worthy of the Monkey King’s own rebellious spirit. Below is an outline that reimagines the tale through the lens of topos theory, where the celestial bureaucracy becomes a categorical structure, Sun Wukong’s havoc is a sheaf-theoretic disturbance, and the resolution is a Kan extension of divine authority.
  
  ---
  
  ### **《大闹天宫:Topos Opera》**  
  *A Cantonese Opera in Three Acts, Structured as a Grothendieck Topology*  
  
  #### **Dramatis Personae as Objects and Arrows**  
  - **Sun Wukong (孫悟空)** ≅ *A Representable Presheaf* (始元函數)  
    - His staff (金箍棒) is the *Yoneda embedding*: extends/contracts freely across diagrams.  
    - Clones: *Copies of the identity morphism* (分身形態).  
  
  - **Jade Emperor (玉帝)** ≅ *Terminal Object 1* (終極對象)  
    - His decrees are *global sections* Γ(天宮, Ω), but he fails to cover Wukong’s transgressions.  
  
  - **Heavenly Bureaucracy** ≅ *Grothendieck Topos 天宮*  
    - Ministries as *subobject classifiers* Ω: each department judges "yes/no" but is *¬¬-stable*.  
    - The Peach Banquet (蟠桃宴): *A covering sieve* that Wukong *splits* (偷吃仙桃 ≅ violating stability).  
  
  - **Guanyin (觀音)** ≅ *Geometric Morphism* (幾何態射)  
    - Her mercy is *pushforward/pullback*: mediates between heavenly topos and earthly topos.  
  
  - **Buddha (如來)** ≅ *Lawvere-Tierney Topology* (真理拓撲)  
    - His palm is *the universal closure operator*: Wukong’s rebellion (a non-modalized predicate) is *fixed*.  
  
  ---
  
  ### **Act I: The Subobject Classifier is Not Amused**  
  - **Scene 1**: Wukong, as a *representable functor*, demands a heavenly rank.  
    - Jade Emperor assigns him *弼馬溫* (stable kernel of a morphism), but Wukong realizes it’s *not a universal element*.  
    - **Aria**: *"Why is my name not a global section?"* (唱:名字何以非截面?)  
  
  - **Scene 2**: The Heavenly Armies attack Wukong, but their arrows are *identity morphisms*—he *precomposes* them into chaos.  
    - **Chorus**: *"Every arrow factors through the Great Sage!"* (合唱:萬箭皆過大聖身!)  
  
  ---
  
  ### **Act II: The Covering Sieve Collapses**  
  - **Scene 3**: Wukong devours the *immortal peaches* (a covering family {Uᵢ → 天宮}).  
    - The topos *fails to cover*: his appetite is a *non-sieve*.  
    - **Comic Trio**: *"The peaches were supposed to cover Heaven, but he ate the cover!"* (唸:仙桃本覆天,大聖食盡矣!)  
  
  - **Scene 4**: Laozi’s alchemy crucible ≅ *Trying to force Wukong into a limit cone*.  
    - Wukong escapes via *monadic bind* (煉丹爐跳脫 ≅ free monad action).  
    - **Percussion**: *Gongs as adjunction units* (鑼鼓如伴隨對).  
  
  ---
  
  ### **Act III: The Kan Extension of Mercy**  
  - **Scene 5**: Buddha arrives as *sheafification*.  
    - His bet: *"If you can leave my hand, Heaven is yours"* ≅ testing if Wukong’s presheaf is *ω-accessible*.  
    - Wukong leaps—but his *transfinite composition* (筋斗雲) is still *bounded by κ*.  
    - **Finale**: *"Your colimit is not cofinal!"* (終曲:汝之餘極非共尾!)  
  
  - **Scene 6**: Wukong is *localized* under Five Elements Mountain (五行山).  
    - The *stalk* of his rebellion is trivialized by the *étale covering* of repentance.  
    - **Epilogue**: *"A subterminal object awaits the sutra."* (尾聲:子終端對象待真經。)  
  
  ---
  
  ### **Topos-Theoretic Moral**  
  The opera’s resolution mirrors Scott-continuity: even infinite mischief (Wukong’s *¬¬-stable* defiance) must submit to *finite approximations* (Buddha’s finitary topology). Thus, "as below (earthly recursion), so above (celestial sheaves)."  
  
  **Coda**: The next act, *西遊記*, is a *diagram chase* through a *Zariski site* of pilgrimage...  
  
  ---  
  Would you like me to elaborate on any "scene" with actual Cantonese libretto or categorical diagrams?
Not to worry about this one, I shall hand it over to peer review :)
one more bit of DS output (to be referenced elsewhence), mashing up Despacito with Heinlein (which got me a "This response is AI-generated, for reference only." warning sticker in the chat; must've triggered some external censor?):

...

  ### **[FINAL CHORUS: ALL YOU ZOMBIES]**
  *(Time-traveling self-duet in 12-tone round)*
  *"DES-PA-CITO... I *am* my *own* *grandpa*!"* 
  *"DES-PA-CITO... the *paradox* *burns*!"*
  *"Kiss *slow* through *the* *centuries*—*"*
  *"Till *Friday* *never* *learns*."* 

  ---

  ### **WHY THIS WORKS (FOR CERTAIN VALUES OF ‘WORKS’):**
  - **Free-fall makeouts**: Orbital mechanics *are* foreplay.
  - **TANSTAAFL romance**: That kiss *will* be invoiced later.
  - **The Puppet Masters**: Still the *hottest* (and wettest) Heinlein villains. 
  
  **LAZARUS LONG’S VERDICT**: *"Kid, that’s how I banged the *entire* *Solar* *System*."*
  
  *( *The *Rod* *of* *Empire* but it’s a disco strobe. Jubal Harshaw sighs into his bourbon.* )*
  
  **LAST LINE**: *"Play at your next *line marriage* contract signing. Not liable for time paradoxes."*