井字過三關

2010-06-27 9:44 pm
證明或否定 :

在井字過三關遊戲中,先手無必勝策略。

回答 (6)

2010-06-28 6:58 am
✔ 最佳答案
答案:無必勝。
---------------------------
証:
情況一:先手(○)先放四個角位

[○] [ ] [○]
[ ] [ ] [ ]
[○] [ ] [○]

後手應對:
[○] [ ] [ ]
[ ] [X] [ ](對稱性只顯示左上)
[ ] [ ] [ ]
-----------------------------
 [○] [ ] [ ] [○] [ ] [ ] [○] [ ] [X]
→[ ] [X] [ ]→[X] [X] [○]→[X] [X] [○]→和局
 [ ] [ ] [○] [ ] [ ] [○] [○] [ ] [○](對稱情況亦一樣)
            
 [○] [ ] [○] [○] [X] [○] 
→[ ] [X] [ ]→[ ] [X] [ ]→和局
 [ ] [ ] [ ] [ ] [○] [ ]

 [○] [ ] [ ] [○] [X] [○] 
→[○] [X] [ ]→[○] [X] [ ]→和局
 [ ] [ ] [ ] [X] [○] [ ]

 [○] [ ] [ ] [○] [ ] [X] [○] [ ] [X]
→[ ] [X] [○]→[ ] [X] [○]→[X] [X] [○]→和局
 [ ] [ ] [ ] [○] [ ] [ ] [○] [ ] [ ]
-----------------------------
∴情況一的任何情況下,都可被後手控制至和局。
=============================
情況二:先手(○)先放於中間位。

[ ] [ ] [ ]
[ ] [○] [ ]
[ ] [ ] [ ]

應對:
[X] [ ] [ ]
[ ] [○] [ ]
[ ] [ ] [ ]
-----------------------------
 [X] [ ] [ ] [X] [ ] [ ]
→[ ] [○] [ ]→[○] [○] [X]→和局
 [ ] [ ] [○] [X] [ ] [○]

 [X] [○] [ ] [X] [○] [ ] [X] [○] [ ]
→[ ] [○] [ ]→[ ] [○] [○]或[ ] [○] [ ]
 [ ] [ ] [ ] [ ] [X] [ ] [○] [X] [ ]
         ↓      ↓
       [X] [○] [X] [X] [○] [X]
       [X] [○] [○]或[ ] [○] [ ]→和局
       [○] [X] [○] [○] [X] [ ]

 [X] [ ] [ ] [X] [○] [X]
→[ ] [○] [ ]→[ ] [○] [ ]→和局
 [○] [ ] [ ] [○] [X] [ ]

 [X] [ ] [ ] [X] [○] [X]
→[ ] [○] [○]→[X] [○] [○]→和局
 [ ] [ ] [ ] [○] [X] [○]
-----------------------------
∴情況二的任何情況,都亦可被後手控制至和局。
=============================
情況三:先手(○)先放於
[ ] [○] [ ]
[○] [ ] [○]四個位置。
[ ] [○] [ ]

應對:
[ ] [ ] [ ]
[○] [X] [ ]
[ ] [ ] [ ]
-----------------------------
 [ ] [ ] [ ] [○] [ ] [ ] [○] [ ] [ ]
→[○] [X] [○]→[○] [X] [○]→[○] [X] [○]→先手負
 [ ] [ ] [ ] [ ] [ ] [X] [X] [ ] [X]

 [ ] [ ] [ ] [ ] [ ] [○]
→[○] [X] [ ]→[○] [X] [X]→和局
 [ ] [ ] [○] [X] [ ] [○]

 [○] [ ] [ ] [○] [X] [○]
→[○] [X] [ ]→[○] [X] [ ]→和局
 [ ] [ ] [ ] [X] [○] [ ]

 [ ] [○] [ ] [ ] [○] [ ] [X] [○] [○]
→[○] [X] [ ]→[○] [X] [ ]→[○] [X] [X]→和局
 [ ] [ ] [ ] [X] [ ] [ ] [X] [○] [○]
-----------------------------
∴情況三之所有場合都可被後手破解至和局(甚至先手負)。
=============================
∴綜合上述三個情況(全部情況):
 在井字過三關遊戲中先手無必勝策略。
*注意對稱之情況
討厭的字數限制……
2010-07-07 1:15 am
利用對稱關係及窮舉法
2010-07-04 7:48 pm
(1 (2 (3
(4 (5 (6
(7 (8 (9

你走(5 , 再走(1 / (3 / (7 / (9,好有可能會和局或你勝,千萬不要走(2 / (4 / (6 / (8! 最多只可和局或你輸。
參考: me
2010-06-27 11:11 pm
本人自行研究到井字過三關既遊戲"""必定不會輸"""的步法..

先行的..係有贏同打和既機會

後行的..係有輸同打和既機會

咁我定先行既係 A /後行既係 B
先講 A 的那位..想贏的話..第一步一定唔可以行中間..係行角落頭..

正常 B 的那位..佢會有兩種行法..一:中間..二:唔係中間

B>佢行中間的話...會面對打和同輸的結果

B>但佢唔行中間的話..會面對必輸的結果...點解咁講呢..?

因為假若

  X║  ║O< 第二或第三步也可...只要放角落
 ══╬══╬══
   ║  ║
 ══╬══╬══
  O║ X║O <第一步
^這是B的第一步或第二步..結果也會面臨A的兩頭蛇
  
圖畫得唔令..請見諒!!

A>只要放左下角同右上角..B的步法會被牽制住


以上這情況會出現兩頭蛇


以下的...B想化解以上的情況只要把第一步放中間就可以了

   ║  ║O 
 ══╬══╬══
    ║X ║
  ══╬══╬══
   ║  ║O 

圖畫得唔令..請見諒!!

所以....總結就係..想行就要行先..但後下的唔想輸.跟以上步法就可以了..

2010-06-30 02:44:52 補充:
其實基本上...想係井字過三關贏的話..除非碰上對手唔識玩或唔知步法...否則結果都只會打
和,

另外打漏左係第二幅圖到:
講到B行中間只可以化解第一幅圖既陷阱..

但B其實都有第二步既陷阱未解決..
  A第二步
  V
  O║  ║X <B第二步
 ══╬══╬══
   ║X ║  <B中間第一步
 ══╬══╬══
  O║  ║O<A第一步
  ^
  A第三步>之後就會出現兩頭蛇..

先講明..我既解說”只可用於唔熟井字過三關既人”

2010-06-30 02:45:34 補充:
字數所限..所以要再POST..請見諒

就以上情況:假如你有機會做到B既話..B係”第二步個陣”只要唔行角落頭就可以

  A第二步
  V
  O║  ║
 ══╬══╬══
   ║X ║  <B中間第一步
 ══╬══╬══
   ║X ║O<A第一步
   ^
   B既第二步..B第二步除左呢個方位之外仲可以行”上/左/右”呢幾個黎化解

但只要A/B都係高手的話..就沒對下去的意義了..

因結果會是”打平手”
參考: 自己經驗, 自己, 自己
2010-06-27 10:30 pm
先手易勝

但在每個人都知道每一種變數的時候
過三關一定是打和的
2010-06-27 10:27 pm
To prove this statement is correct, we should prove the one who put first may lose.

Method 1:

the one who put first let other wins.

Method 2:

X puts first and Y puts second.
Assume that X and Y are very clever.

(a) (b) (c)
(d) (e) (f)
(g) (h) (i)

If X puts a, Y should put not put b and d in order to stop X win, because X will put e
If X puts b, Y can stop X win by putting any place.
If X puts e, Y should not put b,d,f,h n order to stop X win, because X will put a,c,g,i

If follow the above order, X will not win!!!

2010-07-10 23:14:02 補充:
a = c,g,i
b = d,f,h
參考: N/A


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