1. L10. Unify Program in Java
Unify.java

2. String matching: string1 = string2
e.g. “rose” = “rose” if string1.equals(string2)
“I am Rose” = “I am Rose”
“I am ?x” = “I am Rose”
“I am ?x” = “?y am Rose”
I = ?y
am = am
?x = Rose ?
e.g. ?x is ?y and ?x
Rose is rose and ?y
?x = Rose
?y = rose
?x = ?y

3. Output Output from Matching.java ?x is ?y and ?x Rose is rose and ?y
false
Output from Unify.java
{?y=rose, ?x=Rose}
true

4. ? ? Token matching: token1 = token2 Three pairs of tokens’ matching:
e.g. two strings’ matching, “I am ?x” = “?y am Rose”
Three pairs of tokens’ matching:
I = ?y
am = am
?x = Rose
64: boolean tokenMatching(String token1,String token2){
65: if(token1.equals(token2)) return true;
66: if( var(token1) && !var(token2))
67: return varMatching(token1,token2);
68: if(!var(token1) && var(token2))
69: return varMatching(token2,token1);
70: return false;
71: }
73: boolean varMatching(String vartoken,String token){
74: if(vars.containsKey(vartoken)){
75: if(token.equals(vars.get(vartoken))){
76: return true;
77: } else {
78: return false;
79: }
80: } else {
81: vars.put(vartoken,token);
82: }
83: return true;
84: } ? ?
86: boolean var(String str1){
87: // 先頭が ? なら変数
88: return str1.startsWith("?");
89: }
27: Matcher(){
28: vars = new Hashtable();
29: }

5. Exercises
Understand the program (Unify.java) and compare the execution results from Matching.java and Unify.java.
Answer the following questions:
(1) What does the method, replaceBuffer(), do?
(2) What does the method, replaceBindings(), do?
3. Modify the program (Unify.java) so that the program (Unify1.java) can do the following matching as well .
e.g.
?x is ?y and ?x
Rose is rose and ?y
?x is ?y and ?x name(?x)
Rose is rose and ?y name(Rose)