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@@ -637,15 +657,15 @@ <h1>2026-01-07 | tkwa model</h1> |
637 | 657 | intelligence -->|??| economic_value["economic value"] |
638 | 658 | intelligence -->|??| RD</code></pre> |
639 | 659 | </section> |
640 | | -<section id="jones-model" class="level1"> |
| 660 | +<section id="jones-model" class="level1 page-columns page-full"> |
641 | 661 | <h1>2026-01-13 | Jones model</h1> |
642 | 662 | <p>Basic model with accumulating ideas: <span class="math display">\[\begin{gathered}\dot{A}=R^{\gamma}\\ |
643 | 663 | \xymatrix{*++[F]{R\&D} \ar[r] & *++[F]{\Delta algorithms}\ar[r] & *++[F]{algorithms}} |
644 | 664 | \end{gathered}\]</span></p> |
645 | | -<p>Model with shoulders/armpits of giants: <span class="math display">\[\begin{gathered}\dot{A}=R^{\gamma}A^{1-\beta}\\ |
| 665 | +<p>Model with shoulders/armpits of giants (Jones model):<a href="#fn2" class="footnote-ref" id="fnref2" role="doc-noteref"><sup>2</sup></a> <span class="math display">\[\begin{gathered}\dot{A}=R^{\gamma}A^{1-\beta}\\ |
646 | 666 | \xymatrix{*++[F]{R\&D} \ar[r] & *++[F]{\Delta knowledge}\ar[r] & *++[F]{knowledge}\ar@/^2em/[l]} |
647 | 667 | \end{gathered}\]</span></p> |
648 | | -<p>Recursive self-improvement, where knowledge actually helps R&D: <span class="math display">\[\begin{gathered}\dot{A}=R^{\gamma}\\ |
| 668 | +<div class="no-row-height column-margin column-container"><div id="fn2"><p><sup>2</sup> This was introduced by <span class="citation" data-cites="jones1995rd">Jones (<a href="#ref-jones1995rd" role="doc-biblioref">1995</a>)</span>, where there are diminishing returns to knowledge, whereas Romer (1990) had assumed no diminishing returns to knowledge, <span class="math inline">\(\beta=0\)</span>.</p></div></div><p>Recursive self-improvement, where knowledge actually helps R&D: <span class="math display">\[\begin{gathered}\dot{A}=R^{\gamma}\\ |
649 | 669 | \xymatrix{*++[F]{R\&D} \ar[r] & *++[F]{\Delta knowledge}\ar[r] & *++[F]{knowledge}\ar@/^2em/[l]\ar@/^3em/[ll]} |
650 | 670 | \end{gathered}\]</span></p> |
651 | 671 | <dl> |
@@ -685,35 +705,50 @@ <h2 class="anchored" data-anchor-id="metaphors">metaphors</h2> |
685 | 705 | <dl> |
686 | 706 | <dt>Drawing balls from an urn.</dt> |
687 | 707 | <dd> |
688 | | -There’s some distribution of values, then you get a very nice expression. The expected value of <span class="math inline">\(N\)</span> draws just depends on the distribution of values <span class="math inline">\(v\)</span>, & the extreme-value distribution. This is exactly Kortum (1997). |
| 708 | +There’s some distribution of values, then you get a very nice expression. The expected value of <span class="math inline">\(N\)</span> draws just depends on the extreme value distribution of <span class="math inline">\(f(v)\)</span>. This is exactly Kortum (1997). |
689 | 709 | </dd> |
690 | 710 | <dt>A tool factory makes better tools.</dt> |
691 | 711 | <dd> |
692 | 712 | I think this is Jones’ metaphor. <em>Distinct</em> from Kortum, because the returns to search now depends on the stock of ideas. |
693 | 713 | </dd> |
694 | | -<dt>Lego.</dt> |
| 714 | +<dt>Machine tools and regular tools</dt> |
| 715 | +<dd> |
| 716 | +<ol type="1"> |
| 717 | +<li>The Dutch make machine tools.</li> |
| 718 | +<li>The machine tools make regular tools.</li> |
| 719 | +<li>The regular tools make products.</li> |
| 720 | +</ol> |
| 721 | +<p>At some point the machine tools become good enough to make themselves, but it’s a discrete jump.</p> |
| 722 | +</dd> |
| 723 | +<dt>Lego - combining ideas.</dt> |
695 | 724 | <dd> |
696 | 725 | Weitzmann’s recombinant search is like this: you combine ideas to make new ideas, now you have a larger stock of ideas to combine. |
697 | 726 | </dd> |
698 | 727 | <dt>Recipes.</dt> |
699 | 728 | <dd> |
700 | | -You try out recipes, which are combinations of prior recipes. <span class="citation" data-cites="jones2023recipes">@jones2023recipes</span> |
| 729 | +You try out recipes, which are combinations of prior recipes. <span class="citation" data-cites="jones2023recipes">Jones (<a href="#ref-jones2023recipes" role="doc-biblioref">2023</a>)</span> – something like a reconciliation of Weitzman & Kortum. |
701 | 730 | </dd> |
702 | 731 | <dt>Blacksmith.</dt> |
703 | 732 | <dd> |
704 | | -You have a hammer and you spend time making horseshoes, or working on a new hammer. |
705 | | -</dd> |
706 | | -<dd> |
707 | | -A harder hammer both (1) makes horseshoes faster, or (2) makes your hammer still harder. |
| 733 | +<p>You have a hammer and you spend time making horseshoes, or working on a new hammer.</p> |
| 734 | +<p>A harder hammer both (1) makes horseshoes faster, or (2) makes your hammer still harder.</p> |
708 | 735 | </dd> |
709 | 736 | </dl> |
710 | 737 |
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711 | 738 |
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| 739 | + |
712 | 740 | </section> |
713 | 741 | </section> |
714 | 742 |
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715 | 743 |
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716 | | -</main> <!-- /main --> |
| 744 | +<div id="quarto-appendix" class="default"><section class="quarto-appendix-contents" role="doc-bibliography" id="quarto-bibliography"><h2 class="anchored quarto-appendix-heading">References</h2><div id="refs" class="references csl-bib-body hanging-indent" data-entry-spacing="0" role="list"> |
| 745 | +<div id="ref-jones1995rd" class="csl-entry" role="listitem"> |
| 746 | +Jones, Charles I. 1995. <span>“R&d-Based Models of Economic Growth.”</span> <em>Journal of Political Economy</em> 103 (4): 759–84. https://doi.org/<a href="https://doi.org/10.1086/262002">https://doi.org/10.1086/262002</a>. |
| 747 | +</div> |
| 748 | +<div id="ref-jones2023recipes" class="csl-entry" role="listitem"> |
| 749 | +———. 2023. <span>“Recipes and Economic Growth: A Combinatorial March down an Exponential Tail.”</span> <em>Journal of Political Economy</em> 131 (8): 1994–2031. <a href="https://doi.org/10.1086/723631">https://doi.org/10.1086/723631</a>. |
| 750 | +</div> |
| 751 | +</div></section></div></main> <!-- /main --> |
717 | 752 | <script id="quarto-html-after-body" type="application/javascript"> |
718 | 753 | window.document.addEventListener("DOMContentLoaded", function (event) { |
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