diff --git a/Gemfile.lock b/Gemfile.lock
index 3f184ac..1b401cd 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,13 +1,14 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (4.2.10)
-      i18n (~> 0.7)
+    activesupport (6.0.3.3)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (>= 0.7, < 2)
       minitest (~> 5.1)
-      thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
-    addressable (2.5.2)
-      public_suffix (>= 2.0.2, < 4.0)
+      zeitwerk (~> 2.2, >= 2.2.2)
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
@@ -15,43 +16,42 @@ GEM
     colorator (1.1.0)
     commonmarker (0.17.13)
       ruby-enum (~> 0.5)
-    concurrent-ruby (1.1.3)
-    dnsruby (1.61.2)
-      addressable (~> 2.5)
-    em-websocket (0.5.1)
+    concurrent-ruby (1.1.7)
+    dnsruby (1.61.4)
+      simpleidn (~> 0.1)
+    em-websocket (0.5.2)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
-    ethon (0.11.0)
+    ethon (0.12.0)
       ffi (>= 1.3.0)
     eventmachine (1.2.7)
     execjs (2.7.0)
-    faraday (0.15.4)
+    faraday (1.0.1)
       multipart-post (>= 1.2, < 3)
-    ffi (1.9.25)
+    ffi (1.13.1)
     forwardable-extended (2.6.0)
-    gemoji (3.0.0)
-    github-pages (193)
-      activesupport (= 4.2.10)
-      github-pages-health-check (= 1.8.1)
-      jekyll (= 3.7.4)
-      jekyll-avatar (= 0.6.0)
+    gemoji (3.0.1)
+    github-pages (207)
+      github-pages-health-check (= 1.16.1)
+      jekyll (= 3.9.0)
+      jekyll-avatar (= 0.7.0)
       jekyll-coffeescript (= 1.1.1)
-      jekyll-commonmark-ghpages (= 0.1.5)
+      jekyll-commonmark-ghpages (= 0.1.6)
       jekyll-default-layout (= 0.1.4)
-      jekyll-feed (= 0.11.0)
+      jekyll-feed (= 0.13.0)
       jekyll-gist (= 1.5.0)
-      jekyll-github-metadata (= 2.9.4)
-      jekyll-mentions (= 1.4.1)
-      jekyll-optional-front-matter (= 0.3.0)
+      jekyll-github-metadata (= 2.13.0)
+      jekyll-mentions (= 1.5.1)
+      jekyll-optional-front-matter (= 0.3.2)
       jekyll-paginate (= 1.1.0)
-      jekyll-readme-index (= 0.2.0)
-      jekyll-redirect-from (= 0.14.0)
-      jekyll-relative-links (= 0.5.3)
-      jekyll-remote-theme (= 0.3.1)
+      jekyll-readme-index (= 0.3.0)
+      jekyll-redirect-from (= 0.15.0)
+      jekyll-relative-links (= 0.6.1)
+      jekyll-remote-theme (= 0.4.1)
       jekyll-sass-converter (= 1.5.2)
-      jekyll-seo-tag (= 2.5.0)
-      jekyll-sitemap (= 1.2.0)
-      jekyll-swiss (= 0.4.0)
+      jekyll-seo-tag (= 2.6.1)
+      jekyll-sitemap (= 1.4.0)
+      jekyll-swiss (= 1.0.0)
       jekyll-theme-architect (= 0.1.1)
       jekyll-theme-cayman (= 0.1.1)
       jekyll-theme-dinky (= 0.1.1)
@@ -61,88 +61,89 @@ GEM
       jekyll-theme-midnight (= 0.1.1)
       jekyll-theme-minimal (= 0.1.1)
       jekyll-theme-modernist (= 0.1.1)
-      jekyll-theme-primer (= 0.5.3)
+      jekyll-theme-primer (= 0.5.4)
       jekyll-theme-slate (= 0.1.1)
       jekyll-theme-tactile (= 0.1.1)
       jekyll-theme-time-machine (= 0.1.1)
-      jekyll-titles-from-headings (= 0.5.1)
-      jemoji (= 0.10.1)
-      kramdown (= 1.17.0)
-      liquid (= 4.0.0)
-      listen (= 3.1.5)
+      jekyll-titles-from-headings (= 0.5.3)
+      jemoji (= 0.11.1)
+      kramdown (= 2.3.0)
+      kramdown-parser-gfm (= 1.1.0)
+      liquid (= 4.0.3)
       mercenary (~> 0.3)
-      minima (= 2.5.0)
-      nokogiri (>= 1.8.2, < 2.0)
-      rouge (= 2.2.1)
+      minima (= 2.5.1)
+      nokogiri (>= 1.10.4, < 2.0)
+      rouge (= 3.19.0)
       terminal-table (~> 1.4)
-    github-pages-health-check (1.8.1)
+    github-pages-health-check (1.16.1)
       addressable (~> 2.3)
       dnsruby (~> 1.60)
       octokit (~> 4.0)
-      public_suffix (~> 2.0)
+      public_suffix (~> 3.0)
       typhoeus (~> 1.3)
-    html-pipeline (2.9.1)
+    html-pipeline (2.14.0)
       activesupport (>= 2)
       nokogiri (>= 1.4)
     http_parser.rb (0.6.0)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    jekyll (3.7.4)
+    jekyll (3.9.0)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
       i18n (~> 0.7)
       jekyll-sass-converter (~> 1.0)
       jekyll-watch (~> 2.0)
-      kramdown (~> 1.14)
+      kramdown (>= 1.17, < 3)
       liquid (~> 4.0)
       mercenary (~> 0.3.3)
       pathutil (~> 0.9)
       rouge (>= 1.7, < 4)
       safe_yaml (~> 1.0)
-    jekyll-avatar (0.6.0)
-      jekyll (~> 3.0)
+    jekyll-avatar (0.7.0)
+      jekyll (>= 3.0, < 5.0)
     jekyll-coffeescript (1.1.1)
       coffee-script (~> 2.2)
       coffee-script-source (~> 1.11.1)
-    jekyll-commonmark (1.2.0)
+    jekyll-commonmark (1.3.1)
       commonmarker (~> 0.14)
-      jekyll (>= 3.0, < 4.0)
-    jekyll-commonmark-ghpages (0.1.5)
+      jekyll (>= 3.7, < 5.0)
+    jekyll-commonmark-ghpages (0.1.6)
       commonmarker (~> 0.17.6)
-      jekyll-commonmark (~> 1)
-      rouge (~> 2)
+      jekyll-commonmark (~> 1.2)
+      rouge (>= 2.0, < 4.0)
     jekyll-default-layout (0.1.4)
       jekyll (~> 3.0)
-    jekyll-feed (0.11.0)
-      jekyll (~> 3.3)
+    jekyll-feed (0.13.0)
+      jekyll (>= 3.7, < 5.0)
     jekyll-gist (1.5.0)
       octokit (~> 4.2)
-    jekyll-github-metadata (2.9.4)
-      jekyll (~> 3.1)
+    jekyll-github-metadata (2.13.0)
+      jekyll (>= 3.4, < 5.0)
       octokit (~> 4.0, != 4.4.0)
-    jekyll-mentions (1.4.1)
+    jekyll-mentions (1.5.1)
       html-pipeline (~> 2.3)
-      jekyll (~> 3.0)
-    jekyll-optional-front-matter (0.3.0)
-      jekyll (~> 3.0)
+      jekyll (>= 3.7, < 5.0)
+    jekyll-optional-front-matter (0.3.2)
+      jekyll (>= 3.0, < 5.0)
     jekyll-paginate (1.1.0)
-    jekyll-readme-index (0.2.0)
-      jekyll (~> 3.0)
-    jekyll-redirect-from (0.14.0)
-      jekyll (~> 3.3)
-    jekyll-relative-links (0.5.3)
-      jekyll (~> 3.3)
-    jekyll-remote-theme (0.3.1)
-      jekyll (~> 3.5)
-      rubyzip (>= 1.2.1, < 3.0)
+    jekyll-readme-index (0.3.0)
+      jekyll (>= 3.0, < 5.0)
+    jekyll-redirect-from (0.15.0)
+      jekyll (>= 3.3, < 5.0)
+    jekyll-relative-links (0.6.1)
+      jekyll (>= 3.3, < 5.0)
+    jekyll-remote-theme (0.4.1)
+      addressable (~> 2.0)
+      jekyll (>= 3.5, < 5.0)
+      rubyzip (>= 1.3.0)
     jekyll-sass-converter (1.5.2)
       sass (~> 3.4)
-    jekyll-seo-tag (2.5.0)
-      jekyll (~> 3.3)
-    jekyll-sitemap (1.2.0)
-      jekyll (~> 3.3)
-    jekyll-swiss (0.4.0)
+    jekyll-seo-tag (2.6.1)
+      jekyll (>= 3.3, < 5.0)
+    jekyll-sitemap (1.4.0)
+      jekyll (>= 3.7, < 5.0)
+    jekyll-swiss (1.0.0)
     jekyll-theme-architect (0.1.1)
       jekyll (~> 3.5)
       jekyll-seo-tag (~> 2.0)
@@ -170,8 +171,8 @@ GEM
     jekyll-theme-modernist (0.1.1)
       jekyll (~> 3.5)
       jekyll-seo-tag (~> 2.0)
-    jekyll-theme-primer (0.5.3)
-      jekyll (~> 3.5)
+    jekyll-theme-primer (0.5.4)
+      jekyll (> 3.5, < 5.0)
       jekyll-github-metadata (~> 2.9)
       jekyll-seo-tag (~> 2.0)
     jekyll-theme-slate (0.1.1)
@@ -183,60 +184,69 @@ GEM
     jekyll-theme-time-machine (0.1.1)
       jekyll (~> 3.5)
       jekyll-seo-tag (~> 2.0)
-    jekyll-titles-from-headings (0.5.1)
-      jekyll (~> 3.3)
-    jekyll-watch (2.1.2)
+    jekyll-titles-from-headings (0.5.3)
+      jekyll (>= 3.3, < 5.0)
+    jekyll-watch (2.2.1)
       listen (~> 3.0)
-    jemoji (0.10.1)
+    jemoji (0.11.1)
       gemoji (~> 3.0)
       html-pipeline (~> 2.2)
-      jekyll (~> 3.0)
-    kramdown (1.17.0)
-    liquid (4.0.0)
-    listen (3.1.5)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
-      ruby_dep (~> 1.2)
+      jekyll (>= 3.0, < 5.0)
+    kramdown (2.3.0)
+      rexml
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
+    liquid (4.0.3)
+    listen (3.2.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
     mini_portile2 (2.4.0)
-    minima (2.5.0)
-      jekyll (~> 3.5)
+    minima (2.5.1)
+      jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
-    minitest (5.11.3)
-    multipart-post (2.0.0)
-    nokogiri (1.10.8)
+    minitest (5.14.2)
+    multipart-post (2.1.1)
+    nokogiri (1.10.10)
       mini_portile2 (~> 2.4.0)
-    octokit (4.13.0)
+    octokit (4.18.0)
+      faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (2.0.5)
-    rb-fsevent (0.10.3)
-    rb-inotify (0.9.10)
-      ffi (>= 0.5.0, < 2)
-    rouge (2.2.1)
-    ruby-enum (0.7.2)
+    public_suffix (3.1.1)
+    rb-fsevent (0.10.4)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rexml (3.2.4)
+    rouge (3.19.0)
+    ruby-enum (0.8.0)
       i18n
-    ruby_dep (1.5.0)
-    rubyzip (2.0.0)
-    safe_yaml (1.0.4)
-    sass (3.7.2)
+    rubyzip (2.3.0)
+    safe_yaml (1.0.5)
+    sass (3.7.4)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
-    sawyer (0.8.1)
-      addressable (>= 2.3.5, < 2.6)
-      faraday (~> 0.8, < 1.0)
+    sawyer (0.8.2)
+      addressable (>= 2.3.5)
+      faraday (> 0.8, < 2.0)
+    simpleidn (0.1.1)
+      unf (~> 0.1.4)
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     thread_safe (0.3.6)
-    typhoeus (1.3.1)
+    typhoeus (1.4.0)
       ethon (>= 0.9.0)
-    tzinfo (1.2.5)
+    tzinfo (1.2.7)
       thread_safe (~> 0.1)
-    unicode-display_width (1.4.0)
+    unf (0.1.4)
+      unf_ext
+    unf_ext (0.0.7.7)
+    unicode-display_width (1.7.0)
+    zeitwerk (2.4.0)
 
 PLATFORMS
   ruby
@@ -245,4 +255,4 @@ DEPENDENCIES
   github-pages
 
 BUNDLED WITH
-   1.17.1
+   2.1.4
diff --git a/_includes/head.html b/_includes/head.html
index 5f0712e..6a5362f 100644
--- a/_includes/head.html
+++ b/_includes/head.html
@@ -49,17 +49,17 @@
   <link rel="canonical" href="{% if page.canonical %}{{ page.canonical }}{% else %}{{ page.url | replace:'index.html','' | prepend: site.baseurl | prepend: site.url }}{% endif %}">
   <link rel="alternate" type="application/rss+xml" title="{{ site.title }}" href="{{ site.baseurl }}/feed.xml">
 
-  <script type="text/x-mathjax-config"> MathJax.Hub.Config({ TeX: { equationNumbers: { autoNumber: "all" } } }); </script>
-  <script type="text/x-mathjax-config">
-  MathJax.Hub.Config({
-    jax: ["input/TeX", "output/HTML-CSS"],
-    tex2jax: {
-      inlineMath: [ ['$', '$'] ],
-      displayMath: [ ['$$', '$$']],
-      processEscapes: true,
-      skipTags: ['script', 'noscript', 'style', 'textarea', 'pre', 'code']
-    }
-  });
+  <script>
+    MathJax = {
+      tex: {
+        inlineMath: [['\\(', '\\)']],
+        displayMath: [['\\[', '\\]']],
+        tags: 'ams'
+      },
+      svg: {
+        fontCache: 'global'
+      }
+    };
   </script>
-  <script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js" type="text/javascript"></script>
+  <script type="text/javascript" id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-svg.js"></script>
 </head>