It looks like this is a web page, not a feed. I looked for a feed associated with this page, but couldn't find one. Please enter the address of your feed to validate.

Source: https://548858.mit-edu.top/post/8936240715

  1. <!doctype html>
  2. <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" prefix="og: http://ogp.me/ns#">
  3.  
  4.  <head>
  5.    <meta charset="utf-8">
  6.    <meta name="applicable-device" content="pc,mobile">
  7.    <meta name="viewport" content="width=device-width, initial-scale=1">
  8.    <title>Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games #463859404999 (2025-01-31)</title>
  9.    <link rel="canonical" href="https://548858.mit-edu.top/post/8936240715">
  10.    <link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Poppins:wght@400;700&display=swap">
  11.    <link rel="stylesheet" href="https://x.mit-edu.top/static/css/style.css">
  12.    <script src="https://x.mit-edu.top/static/js/lazysizes.min.js" async></script>
  13.    <link rel="shortcut icon" href="/favicon.ico">
  14.    <!-- Open Graph Metadata -->
  15.    <meta property="og:type" content="article" />
  16.    <meta property="og:title" content="Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games" />
  17.    <meta property="og:description" content="Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games #463859404999 (2025-01-31)" />
  18.    <meta property="og:url" content="https://548858.mit-edu.top/post/8936240715" />
  19.    <meta property="og:site_name" content="mit-edu.top" />
  20.    <meta property="og:image" content="https://x.mit-edu.top/static/images/post/5.jpg" />
  21.    <meta property="og:article:published_time" content="2025-01-31T06:18:18Z" />
  22.    <meta property="og:article:author" content="Dr. Steven Mitchell" />
  23.    <meta property="og:article:section" content="mit-edu.top" />
  24.    <meta property="og:article:tag" content="Games, Mobile Games, Video Games" />
  25.    <!-- Schema.org -->
  26.    <script type="application/ld+json">{
  27.            "@context": "https://schema.org",
  28.            "@type": "ScholarlyArticle",
  29.            "headline": "Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games #463859404999 (2025-01-31)",
  30.            "author": {
  31.                "@type": "Person",
  32.                "name": "Dr. Steven Mitchell",
  33.                "affiliation": {
  34.                    "@type": "Organization",
  35.                    "name": "mit-edu.top"
  36.                },
  37.                "url": "https://548858.mit-edu.top/post/8936240715"
  38.            },
  39.            "datePublished": "2025-01-31T06:18:18Z",
  40.            "image": "https://x.mit-edu.top/static/images/post/5.jpg",
  41.            "journal": {
  42.                "@type": "Periodical",
  43.                "name": "mit-edu.top",
  44.                "issn": "10.1069/463859404999"
  45.            },
  46.            "publisher": {
  47.                "@type": "Organization",
  48.                "name": "mit-edu.top",
  49.                "url": "https://548858.mit-edu.top"
  50.            },
  51.            "doi": "463859404999",
  52.            "abstract": "Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games #463859404999 (2025-01-31)",
  53.            "citation": {
  54.                "@type": "CreativeWork",
  55.                "name": "Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games",
  56.                "author": "Dr. Steven Mitchell",
  57.                "datePublished": "2025-01-31T06:18:18Z",
  58.                "url": "https://548858.mit-edu.top/post/8936240715"
  59.            }
  60.        }
  61.    </script>
  62. </head>
  63.  
  64. <body>
  65.    <div class="site-mobile-menu site-navbar-target">
  66.        <div class="site-mobile-menu-header">
  67.            <div class="site-mobile-menu-close">
  68.                <span class="icofont-close js-menu-toggle"></span>
  69.            </div>
  70.        </div>
  71.        <div class="site-mobile-menu-body"></div>
  72.    </div>
  73.    <nav class="site-nav">
  74.        <div class="container">
  75.            <div class="site-navigation">
  76.                <div class="row">
  77.                    <div class="col-md-6 text-center order-1 order-md-2 mb-3 mb-md-0">
  78.                        <a href="https://548858.mit-edu.top" class="logo m-0 text-uppercase">mit-edu.top</a>
  79.                    </div>
  80.                    <div class="col-md-3 order-3 order-md-1">
  81.                    </div>
  82.                </div>
  83.            </div>
  84.        </div>
  85.    </nav>
  86.    <div class="section post-section pt-5">
  87.        <div class="container">
  88.            <div class="row justify-content-center">
  89.                <div class="col-lg-8">
  90.                    <div class="text-center">
  91.                        <img src="https://x.mit-edu.top/static/images/user/5.jpg" alt="Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games" title="Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games" class="author-pic img-fluid rounded-circle mx-auto">
  92.                    </div>
  93.                    <span class="d-block text-center">Steven Mitchell</span>
  94.                    <span class="date d-block text-center small text-uppercase text-black-50 mb-5">2025-01-31</span>
  95.                    <h2 class="heading text-center">Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games</h2>
  96.                    <p class="lead mb-4 text-center">Thanks to Steven Mitchell for contributing the article "Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games".
  97.                    </p>
  98.                    <img src="https://x.mit-edu.top/static/images/post/5.jpg" alt="Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games" title="Learning from Sparse Rewards: AI Strategies in Puzzle-Based Mobile Games" class="img-fluid rounded mb-4 lazyload">
  99.                    <p>The storytelling in video games has matured into an art form, offering players complex narratives filled with rich characters, moral dilemmas, and emotionally resonant experiences that rival those found in literature and cinema. Players are no longer passive consumers but active participants in interactive narratives, shaping the outcome of stories through their choices and actions. This interactive storytelling blurs the line between player and protagonist, creating deeply personal and immersive narratives that leave a lasting impact.</p>
  100. <p>This research investigates how mobile gaming influences cognitive skills such as problem-solving, attention span, and spatial reasoning. It analyzes both positive and negative effects, providing insights into the potential educational benefits and drawbacks of mobile gaming.</p>
  101. <p>This research investigates the cognitive benefits of mobile games, focusing on how different types of games can enhance players’ problem-solving abilities, decision-making skills, and critical thinking. The study draws on cognitive psychology, educational theory, and game-based learning research to examine how game mechanics, such as puzzles, strategy, and role-playing, promote higher-order thinking. The paper evaluates the potential for mobile games to be used as tools for educational development and cognitive training, particularly for children, students, and individuals with cognitive impairments. It also considers the limitations of mobile games in fostering cognitive development and the need for a balanced approach to game design.</p>
  102. <p>Esports, the competitive gaming phenomenon, has experienced an unprecedented surge in popularity, evolving into a multi-billion-dollar industry with professional players competing for lucrative prize pools in tournaments watched by millions of viewers worldwide. The rise of esports has not only elevated gaming to a mainstream spectacle but has also paved the way for new career opportunities and avenues for aspiring gamers to showcase their skills on a global stage.</p>
  103. <p>The gaming industry's commercial landscape is fiercely competitive, with companies employing diverse monetization strategies such as microtransactions, downloadable content (DLC), and subscription models to sustain and grow their player bases. Balancing player engagement with revenue generation is a delicate dance that requires thoughtful design and consideration of player feedback.</p>
  104.  
  105.                    <p>
  106.                    <a href="/redirect/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">Link</a>
  107.                    </p>
  108.                    <p><a href="https://www.linegames.org/" target="_blank" class="custom-link">External link</a>
  109. <a href="https://www.iliiili.com/" target="_blank" class="custom-link">External link</a>
  110. <a href="https://www.digwow.net/" target="_blank" class="custom-link">External link</a>
  111. <a href="https://www.free-giftcodes.com/" target="_blank" class="custom-link">External link</a>
  112. <a href="https://www.gifthub.com.ru/" target="_blank" class="custom-link">External link</a>
  113. <a href="https://050544204944-edu.iliiili.com/" target="_blank" class="custom-link">External link</a>
  114. <a href="https://022315912307-edu.digwow.net/" target="_blank" class="custom-link">External link</a>
  115. <a href="https://210285180135-edu.free-giftcodes.com/" target="_blank" class="custom-link">External link</a>
  116. <a href="https://665060462703-edu.gifthub.com.ru/" target="_blank" class="custom-link">External link</a>
  117. <a href="https://205435267385-gov.iliiili.com/" target="_blank" class="custom-link">External link</a>
  118. <a href="https://803917474070-gov.digwow.net/" target="_blank" class="custom-link">External link</a>
  119. <a href="https://027398618262-gov.free-giftcodes.com/" target="_blank" class="custom-link">External link</a>
  120. <a href="https://789517197489-gov.gifthub.com.ru/" target="_blank" class="custom-link">External link</a>
  121. <a href="https://236744846586-gov-edu.iliiili.com/" target="_blank" class="custom-link">External link</a>
  122. <a href="https://447273551403-gov-edu.digwow.net/" target="_blank" class="custom-link">External link</a>
  123. <a href="https://213061995669-gov-edu.free-giftcodes.com/" target="_blank" class="custom-link">External link</a>
  124. <a href="https://054712357084-gov-edu.gifthub.com.ru/" target="_blank" class="custom-link">External link</a>
  125. <a href="https://439680902309-edu.iliiili.com/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  126. <a href="https://508065960431-edu.digwow.net/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  127. <a href="https://676484828896-edu.free-giftcodes.com/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  128. <a href="https://897128078884-edu.gifthub.com.ru/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  129. <a href="https://481425692330-gov.iliiili.com/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  130. <a href="https://813603392005-gov.digwow.net/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  131. <a href="https://803791139281-gov.free-giftcodes.com/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  132. <a href="https://850093175545-gov.gifthub.com.ru/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  133. <a href="https://link.naver.com/bridge?875185776045&amp;url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  134. <a href="https://link.naver.com/bridge?169098274373&amp;url=https://naver169098274373-edu.digwow.net" target="_blank" class="custom-link">External link</a>
  135. <a href="https://link.naver.com/bridge?790255842361&amp;url=https://naver790255842361-edu.iliiili.com" target="_blank" class="custom-link">External link</a>
  136. <a href="https://link.naver.com/bridge?939543150169&amp;url=https://naver939543150169-edu.1717173.xyz" target="_blank" class="custom-link">External link</a>
  137. <a href="https://link.naver.com/bridge?096424794829&amp;url=https://naver096424794829-edu.gifthub.com.ru" target="_blank" class="custom-link">External link</a>
  138. <a href="https://link.naver.com/bridge?313659843707&amp;url=https://naver313659843707-gov.digwow.net" target="_blank" class="custom-link">External link</a>
  139. <a href="https://link.naver.com/bridge?122139148781&amp;url=https://naver122139148781-gov.iliiili.com" target="_blank" class="custom-link">External link</a>
  140. <a href="https://link.naver.com/bridge?260653694969&amp;url=https://naver260653694969-gov.1717173.xyz" target="_blank" class="custom-link">External link</a>
  141. <a href="https://link.naver.com/bridge?944224937250&amp;url=https://naver944224937250-gov.gifthub.com.ru" target="_blank" class="custom-link">External link</a>
  142. <a href="https://link.naver.com/bridge?265144260336&amp;url=https://naver265144260336-gov-edu.digwow.net" target="_blank" class="custom-link">External link</a>
  143. <a href="https://link.naver.com/bridge?695092996319&amp;url=https://naver695092996319-gov-edu.iliiili.com" target="_blank" class="custom-link">External link</a>
  144. <a href="https://link.naver.com/bridge?813548665189&amp;url=https://naver813548665189-gov-edu.1717173.xyz" target="_blank" class="custom-link">External link</a>
  145. <a href="https://link.naver.com/bridge?506640309909&amp;url=https://naver506640309909-gov-edu.gifthub.com.ru" target="_blank" class="custom-link">External link</a>
  146. <a href="https://blog-108840721085.gifthub.news/" target="_blank" class="custom-link">External link</a>
  147. <a href="https://blog-942460411085.jp-edu.sbs/" target="_blank" class="custom-link">External link</a>
  148. <a href="https://blog-016007927801.kr-edu.sbs/" target="_blank" class="custom-link">External link</a>
  149. <a href="https://blog-874982577823.krlinkedin.sbs/" target="_blank" class="custom-link">External link</a>
  150. <a href="https://blog-965073685386.mit-edu.sbs/" target="_blank" class="custom-link">External link</a>
  151. <a href="https://blog-089769947445.mit-edu.buzz/" target="_blank" class="custom-link">External link</a>
  152. <a href="https://blog-693386673280.mit-edu.tech/" target="_blank" class="custom-link">External link</a>
  153. <a href="https://blog-658287985851.mit-edu.site/" target="_blank" class="custom-link">External link</a>
  154. <a href="https://blog-756490050498.mit-edu.top/" target="_blank" class="custom-link">External link</a>
  155. <a href="https://blog-166484459377.usa-gov.top/" target="_blank" class="custom-link">External link</a>
  156. <a href="https://research-065541727476.mit-edu.pp.ua/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  157. <a href="https://research-572522438087.harvard-edu.pp.ua/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  158. <a href="https://research-522450266811.stanford-edu.pp.ua/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  159. <a href="https://research-993630388540.cambridge-edu.pp.ua/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  160. <a href="https://research-794602455701.berkeley-edu.pp.ua/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  161. <a href="https://research-727409509872.oxford-edu.pp.ua/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  162. <a href="https://research-801666746216-edu.wwv.pp.ua/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  163. <a href="https://research-552032115956-edu.sean.pp.ua/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  164. <a href="https://research-916804185251-edu.line.pp.ua/?url=https://548858.mit-edu.top/post/8936240715" target="_blank" class="custom-link">External link</a>
  165. </p>
  166.                    <div class="row mt-5 pt-5 border-top">
  167.                    </div>
  168.                </div>
  169.            </div>
  170.        </div>
  171.    </div>
  172.    <div class="section pb-0">
  173.        <div class="container">
  174.            <div class="row">
  175.                <div class="col-lg-12">
  176.                    <h2 class="heading">Related</h2>
  177.                </div>
  178.            </div>
  179.            <div class="row justify-content-center">
  180.                <div class="col-lg-12">
  181.                    <div class="post-entry d-md-flex small-horizontal mb-5">
  182.                        <div class="me-md-5 thumbnail mb-3 mb-md-0">
  183.                            <a href="https://548858.mit-edu.top/post/5098241376">
  184.                            <img src="https://x.mit-edu.top/static/images/post/5.jpg" alt="Quantifying the Impact of In-Game Advertisements on Player Immersion" title="Quantifying the Impact of In-Game Advertisements on Player Immersion" class="img-fluid lazyload">
  185.                            </a>
  186.                        </div>
  187.                        <div class="content">
  188.                            <div class="post-meta mb-3">
  189.                                <a href="https://blog-5098241376.mit-edu.top/post/5098241376/" target="_blank">
  190.                                <span class="date">2025-01-31</span>
  191.                                </a>
  192.                            </div>
  193.                            <h2 class="heading"><a href="https://548858.mit-edu.top/post/5098241376">Quantifying the Impact of In-Game Advertisements on Player Immersion</a></h2>
  194.                            <p class="info">This study analyzes the psychological effects of competitive mechanics in mobile games, focusing on how competition influences player motivation, achievement, and social interaction. The research examines how competitive elements, such as leaderboards, tournaments, and player-vs-player (PvP) modes, drive player engagement and foster a sense of accomplishment. Drawing on motivation theory, social comparison theory, and achievement goal theory, the paper explores how different types of competition—intrinsic vs. extrinsic, cooperative vs. adversarial—affect player behavior and satisfaction. The study also investigates the potential negative effects of competitive play, such as stress, frustration, and toxic behavior, offering recommendations for designing healthy, fair, and inclusive competitive environments in mobile games.</p>
  195.                            <a href="https://548858.mit-edu.top/post/5098241376" class="post-author d-flex align-items-center">
  196.                                <div class="author-pic">
  197.                                    <img src="https://x.mit-edu.top/static/images/user/5.jpg" alt="Quantifying the Impact of In-Game Advertisements on Player Immersion" title="Quantifying the Impact of In-Game Advertisements on Player Immersion" class="lazyload">
  198.                                </div>
  199.                                <div class="text">
  200.                                    <strong>Patrick Russell</strong>
  201.                                    <span>2025-01-31 published post</span>
  202.                                </div>
  203.                            </a>
  204.                        </div>
  205.                    </div>
  206.                </div>
  207.                <div class="col-lg-12">
  208.                    <div class="post-entry d-md-flex small-horizontal mb-5">
  209.                        <div class="me-md-5 thumbnail mb-3 mb-md-0">
  210.                            <a href="https://548858.mit-edu.top/post/6078543219">
  211.                            <img src="https://x.mit-edu.top/static/images/post/18.jpg" alt="Exploring Neural-Symbolic AI for Decision-Making in Real-Time Strategy Games" title="Exploring Neural-Symbolic AI for Decision-Making in Real-Time Strategy Games" class="img-fluid lazyload">
  212.                            </a>
  213.                        </div>
  214.                        <div class="content">
  215.                            <div class="post-meta mb-3">
  216.                                <a href="https://blog-6078543219.mit-edu.top/post/6078543219/" target="_blank">
  217.                                <span class="date">2025-01-31</span>
  218.                                </a>
  219.                            </div>
  220.                            <h2 class="heading"><a href="https://548858.mit-edu.top/post/6078543219">Exploring Neural-Symbolic AI for Decision-Making in Real-Time Strategy Games</a></h2>
  221.                            <p class="info">This paper examines the rise of cross-platform mobile gaming, where players can access the same game on multiple devices, such as smartphones, tablets, and PCs. It analyzes the technologies that enable seamless cross-platform play, including cloud synchronization and platform-agnostic development tools. The research also evaluates how cross-platform compatibility enhances user experience, providing greater flexibility and reducing barriers to entry for players.</p>
  222.                            <a href="https://548858.mit-edu.top/post/6078543219" class="post-author d-flex align-items-center">
  223.                                <div class="author-pic">
  224.                                    <img src="https://x.mit-edu.top/static/images/user/5.jpg" alt="Exploring Neural-Symbolic AI for Decision-Making in Real-Time Strategy Games" title="Exploring Neural-Symbolic AI for Decision-Making in Real-Time Strategy Games" class="lazyload">
  225.                                </div>
  226.                                <div class="text">
  227.                                    <strong>Ronald Parker</strong>
  228.                                    <span>2025-01-31 published post</span>
  229.                                </div>
  230.                            </a>
  231.                        </div>
  232.                    </div>
  233.                </div>
  234.                <div class="col-lg-12">
  235.                    <div class="post-entry d-md-flex small-horizontal mb-5">
  236.                        <div class="me-md-5 thumbnail mb-3 mb-md-0">
  237.                            <a href="https://548858.mit-edu.top/post/7506429183">
  238.                            <img src="https://x.mit-edu.top/static/images/post/16.jpg" alt="Behavioral Economics of In-Game Auctions: A Multi-Agent Simulation Approach" title="Behavioral Economics of In-Game Auctions: A Multi-Agent Simulation Approach" class="img-fluid lazyload">
  239.                            </a>
  240.                        </div>
  241.                        <div class="content">
  242.                            <div class="post-meta mb-3">
  243.                                <a href="https://blog-7506429183.mit-edu.top/post/7506429183/" target="_blank">
  244.                                <span class="date">2025-01-31</span>
  245.                                </a>
  246.                            </div>
  247.                            <h2 class="heading"><a href="https://548858.mit-edu.top/post/7506429183">Behavioral Economics of In-Game Auctions: A Multi-Agent Simulation Approach</a></h2>
  248.                            <p class="info">This paper explores the potential of mobile games to serve as therapeutic tools in the treatment of mental health conditions, such as anxiety, depression, and PTSD. It examines how game mechanics and immersive environments can be used to provide psychological relief, improve emotional regulation, and facilitate cognitive-behavioral therapy. The study discusses challenges in integrating therapeutic design with traditional game elements and offers recommendations for the development of clinically effective mobile health games.</p>
  249.                            <a href="https://548858.mit-edu.top/post/7506429183" class="post-author d-flex align-items-center">
  250.                                <div class="author-pic">
  251.                                    <img src="https://x.mit-edu.top/static/images/user/16.jpg" alt="Behavioral Economics of In-Game Auctions: A Multi-Agent Simulation Approach" title="Behavioral Economics of In-Game Auctions: A Multi-Agent Simulation Approach" class="lazyload">
  252.                                </div>
  253.                                <div class="text">
  254.                                    <strong>Kathy Peterson</strong>
  255.                                    <span>2025-01-31 published post</span>
  256.                                </div>
  257.                            </a>
  258.                        </div>
  259.                    </div>
  260.                </div>
  261.            </div>
  262.        </div>
  263.    </div>
  264.    <div class="py-5 bg-light mx-md-3 sec-subscribe">
  265.        <div class="container">
  266.            <div class="row">
  267.                <div class="col-lg-12">
  268.                    <h2 class="h4 fw-bold">Subscribe to newsletter</h2>
  269.                </div>
  270.            </div>
  271.            <form class="row">
  272.                <div class="col-md-8">
  273.                    <div class="mb-3 mb-md-0">
  274.                        <input type="email" class="form-control" placeholder="Enter your email">
  275.                    </div>
  276.                </div>
  277.                <div class="col-md-4 d-grid">
  278.                    <input type="submit" class="btn btn-primary" value="Subscribe">
  279.                </div>
  280.            </form>
  281.        </div>
  282.    </div>
  283.    <div class="site-footer">
  284.        <div class="container">
  285.            <div class="row justify-content-center copyright">
  286.                <div class="col-lg-7 text-center">
  287.                    <div class="widget">
  288.                        <p>Copyright &copy;
  289.                            <script>document.write(new Date().getFullYear());</script> All rights reserved.
  290.                        </p>
  291. <p>
  292.    < Top VPS Hosting Choice ><br>
  293.    <a href="https://evolution-host.com?ref=DQgZ6P" target="_blank">
  294.        <img src="https://x.mit-edu.top/static/images/evolution-host.png" alt="Evolution Host" title="Evolution Host" class="evhost lazyload">
  295.    </a>
  296. </p>
  297.                    </div>
  298.                </div>
  299.            </div>
  300.        </div>
  301.    </div>
  302. </body>
  303.  
  304. </html>
Copyright © 2002-9 Sam Ruby, Mark Pilgrim, Joseph Walton, and Phil Ringnalda