Initial Commit

Model.java

+import java.lang.reflect.Field;
+
+public abstract class Model {
+    public abstract boolean sat();
+    public abstract boolean implies(boolean p, boolean q);
+    
+    public String toString() {
+        StringBuilder result = new StringBuilder();
+        try {
+            Field[] fields = this.getClass().getDeclaredFields();
+            for (Field f : fields) {
+                if (f.getType().isArray() && f.getType().getComponentType() == boolean.class) {
+                    f.setAccessible(true);
+                    result.append(f.getName() + " = " + java.util.Arrays.toString((boolean[])f.get(this)));
+                    result.append(", ");
+                }
+            }
+        } catch (IllegalAccessException e) {
+            throw new RuntimeException("This should never happen.  Contact Course Staff!");
+        }
+        result.delete(result.length() - 2, result.length());
+        return "{" + result.toString() + "}";
+    }
+
+    public static boolean[] booleans() {
+        return new boolean[]{true, false};
+    }
+}

README.md

+If you want to use git, you can clone this repository.  If you do not want to
+use git, download the two following Java files.  Note that Model.java is *different*
+than it was on HW1.
+
+- https://gitlab.cs.washington.edu/cse311-17sp/hw2-lying-tas-redux/blob/master/Model.java
+- https://gitlab.cs.washington.edu/cse311-17sp/hw2-lying-tas-redux/blob/master/Situation1NPeople.java

Situation1NPeople.java

+import java.util.List;
+import java.util.ArrayList;
+
+/**
+ * Now, we generalize the work you did on HW 1.  Instead of saying there are a particular
+ * number of people, we will allow an arbitrary number of people in the model.
+ *
+ * Perhaps unsurprisingly, this means that instead of a bunch of boolean variables, we will
+ * be using an *array*.  The important idea here is that the "array" is exactly like the
+ * predicates we've been discussing in class.  In particular, given a "person", the IsTA
+ * array tells us if that person is a TA.
+ *
+ * This time, we make the assumption that the "0th person" is the one who speaks.
+ *
+ * You should begin by copying over your sat implementation from HW1.
+ *
+ * Then, you should fill in correct implementations for allStudentOrTA,
+ * noneStudentAndTA, and someoneIsTA.
+ *
+ * Finally, you should combine your old sat with the three methods you wrote above.
+ **/
+
+
+public class Situation1NPeople {
+    private static class Situation1Model extends Model {
+        private int NUM_PEOPLE;
+        private boolean[] IsTA, IsStudent;
+
+        public Situation1Model(boolean[] IsTA, boolean[] IsStudent) {
+            this.IsTA = IsTA;
+            this.IsStudent = IsStudent;
+
+            this.NUM_PEOPLE = this.IsTA.length;
+        }
+
+        public boolean implies(boolean p, boolean q) {
+            return !p || q;
+        }
+
+        public boolean allStudentOrTA() {
+            // This is not correct!
+            return true;
+        }
+
+        public boolean noneStudentAndTA() {
+            // This is not correct!
+            return true;
+        }
+
+        public boolean someoneIsTA() {
+            // This is not correct!
+            return true;
+        }
+
+        public boolean sat() {
+            // Combine your HW1 implementation with the methods you just wrote.
+            return true;
+        }
+    }
+
+    /** 
+     * This method returns all the Strings made up of T's and F's
+     * of the provided length.
+     **/
+    public static List<String> allTFStrings(int length) {
+        if (length == 0) {
+            List<String> result = new ArrayList<>();
+            result.add("");
+            return result;
+        }
+        else {
+            List<String> newResult = new ArrayList<>();
+            List<String> next = allTFStrings(length - 1);
+            for (String s : next) {
+                newResult.add(s + "T");
+                newResult.add(s + "F");
+            }
+            return newResult;
+        }
+    }
+
+    /**
+     * This method converts a String of "T"s and "F"s to an array
+     * of booleans.
+     **/
+    public static boolean[] TFStringToArray(String bools) {
+        boolean[] result = new boolean[bools.length()];
+        for (int i = 0; i < result.length; i++) {
+            result[i] = bools.charAt(i) == 'T';
+        }
+        return result;
+    }
+
+    /**
+     * This method returns an array of all the models for a particular
+     * number of people.  Why can we allocate the array up-front?  Why
+     * is the size what it is?
+     */
+    public static Model[] allModels(int i) {
+        Model[] models = new Model[(int)Math.pow(2, 2 * i)];
+
+        int idx = 0;
+        for (String taBools : allTFStrings(i)) {
+            for (String studentBools : allTFStrings(i)) {
+                models[idx] = new Situation1Model(TFStringToArray(taBools), TFStringToArray(studentBools));
+                idx++;
+            }
+        }
+        return models;
+    }
+
+    public static void main(String[] args) {
+        for (int i = 2; i < 6; i++) {
+            System.out.println("The models for " + i + " people are...");
+            for (Model model : allModels(i)) {
+                if (model.sat()) {
+                    System.out.println("    " + model);
+                }
+            }
+        }
+    }
+}