# Sleeping Beauty Lab — Probability by experiment

> Probability by experiment (iPhone/iPad app by BEK Service LTD.)

- Source: https://appshunter.io/ios/app/sleeping-beauty-lab/id6777830398 (this page in markdown: same URL + `.md`)
- Developer: [BEK Service LTD](https://appshunter.io/developer/1865488235)
- Category: Education
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 15.0 · 65 MB
- Released: 2026-06-15
- Data updated: 2026-06-22
- User reviews in markdown: https://appshunter.io/ios/app/sleeping-beauty-lab/id6777830398/reviews.md

## What is Sleeping Beauty Lab?

Is the answer one-half or one-third? Sleeping Beauty Lab settles the famous Sleeping Beauty problem the only way that never lies: by running the experiment thousands of times and counting what actually happens.

A coin is flipped. On heads you are woken once; on tails twice, with your memory erased between wakings. You open your eyes. What is the probability the coin came up heads? Halfers say 1/2. Thirders say 1/3. Instead of arguing, watch a live Monte-Carlo simulator tally real awakenings until the numbers speak for themselves.

From that one puzzle, the app opens the whole landscape of anthropic reasoning, the strange logic of reasoning about your own existence:

- Halfer vs thirder, and why each is internally consistent
- SSA and SIA, the two self-sampling assumptions behind them
- The Doomsday Argument and what it really predicts
- The reference-class problem that haunts all of it
- The Presumptuous Philosopher, UN++, Full Non-Indexical Conditioning (FNC), and Anthropic Decision Theory (ADT)

Eighteen interactive screens build the ideas step by step. A betting lab turns abstract credence into concrete wagers, and every claim is backed by experiment or exact arithmetic, never hand-waving.

Features:
- Live Monte-Carlo simulator with adjustable trials
- Benchmark lab comparing strategies side by side
- Day-by-day breakdown of every awakening
- Built-in quiz and a plain-language glossary

Completely free. Fully offline. No account, no ads, no tracking, no data collected. Just you, a coin, and the deepest puzzle in probability.

Whether you are a student, a philosopher, a data scientist, or just argue-at-2am curious, Sleeping Beauty Lab turns a paradox you can debate forever into one you can finally measure.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Remove Ads & Support | $1.99 | one-time |



## Version history (last 1 release)

### 1.0.0 — 2026-06-15

No release notes.

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All apps by BEK Service LTD: https://appshunter.io/developer/1865488235

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-22.*