欢迎来到麦多课文档分享! | 帮助中心 海量文档,免费浏览,给你所需,享你所想!
麦多课文档分享
全部分类
  • 标准规范>
  • 教学课件>
  • 考试资料>
  • 办公文档>
  • 学术论文>
  • 行业资料>
  • 易语言源码>
  • ImageVerifierCode 换一换
    首页 麦多课文档分享 > 资源分类 > PPT文档下载
    分享到微信 分享到微博 分享到QQ空间

    Artificial Intelligence Chapter 21.The Situation Calculus.ppt

    • 资源ID:378586       资源大小:79KB        全文页数:21页
    • 资源格式: PPT        下载积分:2000积分
    快捷下载 游客一键下载
    账号登录下载
    微信登录下载
    二维码
    微信扫一扫登录
    下载资源需要2000积分(如需开发票,请勿充值!)
    邮箱/手机:
    温馨提示:
    如需开发票,请勿充值!快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。
    如需开发票,请勿充值!如填写123,账号就是123,密码也是123。
    支付方式: 支付宝扫码支付    微信扫码支付   
    验证码:   换一换

    加入VIP,交流精品资源
     
    账号:
    密码:
    验证码:   换一换
      忘记密码?
        
    友情提示
    2、PDF文件下载后,可能会被浏览器默认打开,此种情况可以点击浏览器菜单,保存网页到桌面,就可以正常下载了。
    3、本站不支持迅雷下载,请使用电脑自带的IE浏览器,或者360浏览器、谷歌浏览器下载即可。
    4、本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰。
    5、试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。

    Artificial Intelligence Chapter 21.The Situation Calculus.ppt

    1、Artificial Intelligence Chapter 21. The Situation Calculus,(C) 2000, 2001 SNU CSE Biointelligence Lab,2,Outline,Reasoning about States and Actions Some Difficulties Generating Plans Additional Readings and Discussion,(C) 2000, 2001 SNU CSE Biointelligence Lab,3,21.1 Reasoning about States and Action

    2、s,To investigate feature-based planning methods much more thoroughly, richer language to describe features and the constraints among them will be introduced.Generally, a goal condition can be described by any wff in the predicate calculus, and we can determine if a goal is satisfied in a world state

    3、 described by formulas by attempting to prove the goal wff from those formulas.,(C) 2000, 2001 SNU CSE Biointelligence Lab,4,Situation calculus (1/3),A predicate calculus formalization of states, actions, and the effects of actions on states.Our knowledge about states and actions as formulas in the

    4、first-order predicate calculus Then use a deduction system to ask questions such as “Does there exist a state to satisfy certain properties, and if so, how can the present state be transformed into that state by actions” A plan for achieving the desired state.,(C) 2000, 2001 SNU CSE Biointelligence

    5、Lab,5,Situation calculus (2/3),The situation calculus was used in some early AI planning systems. it does not used nowadays. However, the formalism remains important for exposing and helping to clarify conceptual problems.,(C) 2000, 2001 SNU CSE Biointelligence Lab,6,Situation calculus (3/3),In orde

    6、r to describe states in the situation calculus, we reify states. States can be denoted by constant symbols (S0, S1, S2, ), by variables, or by functional expressions. Fluents: the atomic wff can denote relations over states.,(C) 2000, 2001 SNU CSE Biointelligence Lab,7,Example (Figure 21.1),First-or

    7、der predicate calculus On(B,A)On(A,C)On(C,F1)Clear(B) True statement On(B,A,S0)On(A,C,S0)On(C,F1,S0)Clear(B, S0) Prepositions true of all states (x,y,s)On(x,y,s)(y=F1) Clear(y,s) And (s)Clear(F1,s),(C) 2000, 2001 SNU CSE Biointelligence Lab,8,To represent actions and the effects (1/2),Reify the acti

    8、on Actions can be denoted by constant symbols, by variables, or by functional expressions Generally, we can represent a family of move actions by the schema, move(x,y,z), where x, y, and z are schema variables. Imagine a function constant, do, that denotes a function that maps actions and states int

    9、o states. do(,) denotes a function that maps the state-action pair into the state obtained by performing the action denoted by in the state denoted by .,(C) 2000, 2001 SNU CSE Biointelligence Lab,9,To represent actions and the effects (2/2),Express the effects of actions by wffs. There are two such

    10、wffs for each action-fluent pair. For the pair On, move. On(x,y,s)Clear(x,s)Clear(z,s)(xz) On(x,z,do(move(x,y,z),s) And On(x,y,s)Clear(x,s)Clear(z,s)(xz) On(x,z,do(move(x,y,z),s),positive effect axiom,negative effect axiom,preconditions,consequent,(C) 2000, 2001 SNU CSE Biointelligence Lab,10,Effect

    11、 axioms,We can also write effect axioms for the Clear, move pair. On(x,y,s)Clear(x,s)Clear(z,s)(xz)(yz) Clear(y,do(move(x,y,z),s) On(x,y,s)Clear(x,s)Clear(z,s)(xz)(zF1) Clear(z,do(move(x,y,z),s) The antecedents consist of two parts One part expresses the preconditions under which the action can be e

    12、xecuted The other part expresses the condition under which the action will have the effect expressed in the consequent of the axiom.,(C) 2000, 2001 SNU CSE Biointelligence Lab,11,(C) 2000, 2001 SNU CSE Biointelligence Lab,12,21.2.1 Frame Axioms,Not all of the statements true about state do(move(B,A,

    13、F1),S0) can be inferred by the effects axioms. Before the move, such as that C was on the floor and that B was clear are also true of the state after the move. In order to make inferences about these constancies, we need frame axioms for each action and for each fluent that doesnt change as a result

    14、 of the action.,(C) 2000, 2001 SNU CSE Biointelligence Lab,13,21.2.1 Frame Axioms,The frame axioms for the pair, (move, On) On(x,y,s)(xu) On(x,y,do(move(u,y,z),s) (On(x,y,s)(xu)(yz) On(x,y,do(move(u,v,z),s)The frame axioms for the pair, move, Clear Clear(u,s)(uz) Clear(u,do(move(x,y,z),s) Clear(u,s)

    15、(uy) Clear(u,do(move(x,y,z),s),positive frame axioms,negative frame axioms,(C) 2000, 2001 SNU CSE Biointelligence Lab,14,21.2.1 Frame Axioms,Frame axioms are used to prove that a property of a state remains true if the state is changed by an action that doesnt affect that property.Frame problem The

    16、various difficulties associated with dealing with fluents that are not affected by actions.,(C) 2000, 2001 SNU CSE Biointelligence Lab,15,21.2.2 Qualifications,The antecedent of the transition formula describing an action such as move gives the preconditions for a rather idealized case. To be more p

    17、recise, adding other qualification such as Too_heavy(x,s), Glued_down(x,s), Armbroken(s), Qualification problem The difficulty of specifying all of the important qualifications.,(C) 2000, 2001 SNU CSE Biointelligence Lab,16,21.2.3 Ramifications,Ramification problem Keeping track of which derived for

    18、mulas survive subsequent state transitions.,(C) 2000, 2001 SNU CSE Biointelligence Lab,17,21.3 Generating Plans,To generate a plan that achieves some goal, (s), We attempt to prove (s) (s) And use the answer predicate to extract the state as a function of the nested actions that produce it.,(C) 2000

    19、, 2001 SNU CSE Biointelligence Lab,18,Example (Figure 21.1) (1/2),We want a plan that gets block B on the floor from the initial state, S0, given in Figure 21.1. Prove (s) On(B, F1, s) We will prove by resolution refutation that the negation of (s) On(B, F1, s), together with the formulas that descr

    20、ibe S0 and the effects of move are inconsistent. Use an answer predicate to capture the substitutions made during the proof.,(C) 2000, 2001 SNU CSE Biointelligence Lab,19,Example (Figure 21.1) (2/2),On(A,C,S0) On(C,F1,S0) Clear(B,S0) Clear(F1,S0) On(x,y,s)Clear(x,s) Clear(z,s) (xz) On(x,z,do(move(x,

    21、y,z),s),(C) 2000, 2001 SNU CSE Biointelligence Lab,20,Difficulties,If several actions are required to achieve a goal, the action functions would be nested. The proof effort is too large for even simple plan.,(C) 2000, 2001 SNU CSE Biointelligence Lab,21,Additional Readings,Reiter 1991 Successor-state axiom Shanahan 1997 Frame problem Levesque, et al. 1977 GOLOG(alGol in LOGic) Scherl & Levesque 1993 Robot study in Perception Robot Group,


    注意事项

    本文(Artificial Intelligence Chapter 21.The Situation Calculus.ppt)为本站会员(eveningprove235)主动上传,麦多课文档分享仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知麦多课文档分享(点击联系客服),我们立即给予删除!




    关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服 - 联系我们

    copyright@ 2008-2019 麦多课文库(www.mydoc123.com)网站版权所有
    备案/许可证编号:苏ICP备17064731号-1 

    收起
    展开