From aa4eb5b17a5d4da25259a4163eb86400c4c4b52f Mon Sep 17 00:00:00 2001
From: henz <henz@comp.nus.edu.sg>
Date: Mon, 1 Jul 2024 11:48:34 +0800
Subject: [PATCH 1/2] fixes #836

---
 xml/chapter3/section3/subsection4.xml | 53 +++++++++++++++------------
 1 file changed, 29 insertions(+), 24 deletions(-)

diff --git a/xml/chapter3/section3/subsection4.xml b/xml/chapter3/section3/subsection4.xml
index 9d5ca6f62..311d55674 100755
--- a/xml/chapter3/section3/subsection4.xml
+++ b/xml/chapter3/section3/subsection4.xml
@@ -570,21 +570,6 @@ function logical_and(s1, s2) {
 }
     </JAVASCRIPT>
   </SNIPPET>
-  <SNIPPET HIDE="yes">
-    <NAME>logical_or</NAME>
-    <JAVASCRIPT>
-function logical_or(s1, s2) {
-    return s1 === 0 &amp;&amp; s2 === 0
-           ? 0
-           : s1 === 0 || s1 === 1
-           ? s2 === 0 || s2 === 1
-             ? 1
-             : error(s2, "invalid signal")
-           : error(s1, "invalid signal");
-}
-    </JAVASCRIPT>
-  </SNIPPET>
-  
   <PDF_ONLY>
     <!-- Figure moved here from earlier for SICP JS pagination -->
     <!-- Figure code is copy of code earlier in this file in a WEB_ONLY -->
@@ -673,12 +658,32 @@ function and_gate(a1, a2, output) {
       <JAVASCRIPT><JAVASCRIPTINLINE>and_gate</JAVASCRIPTINLINE>.
       </JAVASCRIPT>
     </SPLITINLINE>
-    <SNIPPET HIDE="yes">
-      <NAME>or_gate</NAME>
-      <REQUIRES>get_signal</REQUIRES>
-      <REQUIRES>after_delay</REQUIRES>
-      <REQUIRES>logical_or</REQUIRES>
-      <JAVASCRIPT>
+    <LABEL NAME="ex:3_28"/>
+    <SOLUTION>
+      <SNIPPET>
+	<NAME>logical_or</NAME>
+	<JAVASCRIPT>
+// contributed by GitHub user clean99
+
+function logical_or(s1, s2) {
+    return s1 === 0 &amp;&amp; s2 === 0
+           ? 0
+           : s1 === 0 || s1 === 1
+           ? s2 === 0 || s2 === 1
+             ? 1
+             : error(s2, "invalid signal")
+           : error(s1, "invalid signal");
+}
+	</JAVASCRIPT>
+      </SNIPPET>
+      <SNIPPET>
+	<NAME>or_gate</NAME>
+	<REQUIRES>get_signal</REQUIRES>
+	<REQUIRES>after_delay</REQUIRES>
+	<REQUIRES>logical_or</REQUIRES>
+	<JAVASCRIPT>
+// contributed by GitHub user clean99
+
 function or_gate(a1, a2, output) {
     function or_action_function() {
         const new_value = logical_or(get_signal(a1),
@@ -690,9 +695,9 @@ function or_gate(a1, a2, output) {
     add_action(a2, or_action_function);
     return "ok";
 }
-      </JAVASCRIPT>
-    </SNIPPET>
-    <LABEL NAME="ex:3_28"/>
+	</JAVASCRIPT>
+      </SNIPPET>
+    </SOLUTION>
   </EXERCISE>
   
   <EXERCISE>

From 4e0511ab0276858ce33b23245fd28adf7e0e294d Mon Sep 17 00:00:00 2001
From: henz <henz@comp.nus.edu.sg>
Date: Mon, 1 Jul 2024 14:15:39 +0800
Subject: [PATCH 2/2] fixes #837

---
 xml/chapter3/section3/subsection5.xml | 47 +++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/xml/chapter3/section3/subsection5.xml b/xml/chapter3/section3/subsection5.xml
index ab5b57998..c20841f95 100755
--- a/xml/chapter3/section3/subsection5.xml
+++ b/xml/chapter3/section3/subsection5.xml
@@ -1561,6 +1561,53 @@ const answer = v_prod(v_sum("a", "b"), v_sum("c", "d"));
     expression-oriented style in terms of the imperative implementation,
     it is very difficult to do the converse.</FOOTNOTE>
     <LABEL NAME="ex:3_37"/>
+    <SOLUTION>
+      <SNIPPET>
+	<REQUIRES>make_connector</REQUIRES>
+	<REQUIRES>has_value</REQUIRES>
+	<REQUIRES>for_each_except</REQUIRES>
+	<REQUIRES>inform_about_value</REQUIRES>
+	<REQUIRES>multiplier_2</REQUIRES>
+	<REQUIRES>adder</REQUIRES>
+	<REQUIRES>constant</REQUIRES>
+	<JAVASCRIPT>
+// Solution provided by GitHub user clean99
+
+function cminus(x, y) {
+    const z = make_connector();
+    const u = make_connector();
+    const v = make_connector();
+    constant(-1, u);
+    multiplier(u, y, v);
+    adder(x, v, z);
+    return z;
+}
+
+function cmul(x, y) {
+    const z = make_connector();
+    multiplier(x, y, z);
+    return z;
+}
+
+function cdiv(x, y) {
+    const z = make_connector();
+    const u = make_connector();
+    const v = make_connector();
+    constant(1, v);
+    // y * u = 1 -> u = 1 / y
+    multiplier(y, u, v);
+    multiplier(x, u, z);
+    return z;
+}
+
+function cv(val) {
+    const x = make_connector();
+    constant(val, x);
+    return x;
+}
+	</JAVASCRIPT>
+      </SNIPPET>
+    </SOLUTION>
   </EXERCISE>
 
   <INDEX>propagation of constraints<CLOSE/></INDEX>