Universit degli Studi di Siena Dottorato in Scienze Cognitive

1

• Università degli Studi di Siena- Dottorato in
  Scienze Cognitive
• Gli atomi dellazione e
• le motivazioni della scelta
• Approcci formali al problema della
• selezione dellazione basata sugli scopi,
  dellintenzione e del tentativo.
•  
•  Emiliano Lorini

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Objects of the investigation

• Future-directed Intentions, Intentions in Action,
  Attempts
• Formal analysis and description of practical
  reasoning.
• From the formation of a Future-directed Intention
  to do ? to the formation of the Present-directed
  Intention to ? and to the execution of action ?
  (the Attempt).
• Goal-based Choice and Evaluation of state of
  affairs
• Formal procedure and criterion to attributes
  values of utility to worlds (assignments of truth
  values to propositional atoms) starting from an
  explicit and quantitative representation of
  instrumental and terminal goals.

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• CHAPTER 1
• A formal model of
• Intention and Attempt
•  
•  

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Objectives

• Analysis of the notion of Attempt inside the more
  general framework of Intentional Action theory.
• Formal model of dependence relations between the
  elements of a pragmatic (intentional) plan.
• Analysis of the notion of Achievement Goal and
  Intention.

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Attempts and Actions (1)

• Chisholm (1966) says that the movement of a
  person's arm, when the person moves it, is the
  product of a series of external causes but some
  of event (the attempt), "and presumably one of
  those that took place within the brain, was
  caused by the agent and not by any other events".
• O'Shaughnessy (1973) stresses the bridging role
  of the attempt between the present-directed
  intention and the execution of the action
• Psycho-Psycho Law
• if an agent at an instant in time realizes that
  that instant is an instant at which he intends to
  perform action x, then logically necessarily he
  begins trying to do x at that very moment of
  realization.

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Attempts and Actions (2)

• BASIC ACTIONS VS COMPLEX ACTIONS
• As in Goldman (1970) I assume that basic actions
  include only bodily
• movements (raise the arm, bend the leg, turn the
  sensor etc...) which are
• elements of a general repertoire of agent i 's
  conducts.
• Differently from complex actions, the agent can
  perform a basic
• action ? without necessarily performing some
  other action ß and without
• necessarily believing that some other action ß
  must be performed in order
• to perform ?.
• Example of complex action. The action of Jack
  killing Joe which
• depends on the action of Jack shooting Joe which
  in turn depends on the
• action of Jack pulling the trigger and so on...

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Attempts and Actions (3)

• In this presentation I deal with basic actions of
  a given agent i and leave aside the issue of
  complex actions (therefore every time I use the
  term action I mean basic action.)
• An attempt is the core element of the causal
  process which leads from the present-directed
  intention (Bratman 1987) to the execution of the
  (basic) action in the external world.
• With "agent i attempts to do an action ?", I mean
  that "agent i triggers the execution of action ?
  ", "agent i exerts himself to do action ?.
• GENERAL PRINCIPLE (see also Goldman 1970)
• in order for an action to be effectively
  performed the agent must trigger the action under
  the appropriate preconditions for action
  execution. The fact that the preconditions for
  action execution are holding guarantees that the
  attempt will be successful it will succeed in
  producing the action associated to it

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Attempts and Actions (4)

• Intentional actions and spontaneous conducts
  share the attempt mechanism.
• In this work I focus on intentional attempts
  assuming that an attempt to do ? is always
  produced by the goal (intention) to attempt to do
  ? (see also Vanderveken with respect to this
  hypothesis.)
• Example
• I can attempt to raise the arm having the
  intention to (attempt to) raise the arm (in order
  to signal that I am here) but I can also
  spontaneously attempt to cough (because of some
  bronchial irritation) without having the
  intention to (attempt to) cough.

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Attempts and Actions (5)

• When the attempt is conceived as a pure mental
  (internal) event,
• we should postulate that unsuccessful attempts
  (differently from
• actions) do not change the physical (external)
  world and are not
• perceivable by other agents.
• I do not make here this assumption!
• My category of unsuccessful attempt includes all
  those cases of
• partial execution of a basic action
• Example. An agent who attempts to raise the arm
  and only moves
• the arm of few millimeters since the since the
  arm is tied down.)

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Attempts and Actions (6)
Mind
External world
Present-directed Intention to do ?
Action ? execution
cause
Precond for doing ?
Attempt to do ?
Failure
cause
Not Precond for doing ?
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Mental states dynamics

• Generation of new motivational mental states
  starting from beliefs about necessity and
  pre-existing motivations.
• Persistence property of intentions and goals the
  mental conditions for abandoning a pre-existing
  motivation.
• Relativization property of mental states
  dependence relations between the goals of a
  cognitive system, hierarchically organized in a
  pragmatic plan (the persistance of goal G1 depend
  on the persistance of superior goal G2).

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Other kinds of Attempt and the notion of Trying
(1)

• Attempt as the dubious initiation of an action
  aimed at achieving certain intended
• result (or state of affairs) where
• 1. The object of the doubt (negative expectation)
  is the achievement of the
• intended result or
• 2. The object of the doubt (negative expectation)
  is the feasibility of the action.
• Example Agent i intends to hit the target by
  shooting an arrow with a bow having
• the doubt that if he shoots the arrow with the
  bow then the target will be hit (or
• having the doubt that we will effectively shoots
  the arrow with the bow).

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Other kinds of Attempt and the notion of Trying
(2)

• When an agent is intentionally trying to do some
  action ? the object of
• the present(primary) intention is merely
  epistemic.
• The primary intention is either
• the intention to test if action ? will be
  successfully performed after being triggered or
• the intention to test if the state of the world ?
  will effectively be achieved after the execution
  of action ?.

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LIA-Logic of Intention and Attempt General
properties (1)

• Multi-modal logic of time, attempts, actions,
  goals and beliefs.
• Based on an enhanced version of CTL
  branching-time semantic (Emerson 1990) where we
  can talk about actions.
• The states accessible via access. relation for
  NEXT state are defined by the union of states
  accessible via access. relation for Attempt RX
  ?a?ATT RATT(a).
• Main difference with respect to modal logic of
  action and time (De Nicola et al. 1993, Broersen
  2003, Singh 1998) the atomic action is
  substituted with the more primitive notion atomic
  attempt and the former is defined from the
  latter.

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LIA Axioms (1)

• CTL-standard for time.
• Modal Logic KD45 for goals and beliefs.
• 1. Beli ?i ? ? ? Beli ?i ? ? ?i Beli
  ? (NoForgettingBel)
• Scherl Levesque (2003), Reiter (2001)
• 2. ?i Beli ? ? ??i ? ? Beli ?i ?
  (NoLearningBel)
• 3. Beli ? ? Goali ? CL (1990)
  (Strong-Inclusion)
• 4. Beli ? ? ? Goal ? ? ? Goali ?
  (Weak-Inclusion)
• Frame Correspondance
• ? s, if s RGoal s' then (s RBel s' or ? s", if s
  RGoal s" then s" is s')

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LIA Axioms (2)

• Standard K-axiom of dynamic logic (Harel et al.
  2000).
• 5. lt?gti? def Pre (i, ?) ? ltlt?gtgt i ?
  Definition
• Informally An action a is going to be executed
  iff attempt to do a is going
• to be triggered and the preconditions for
  executing action a hold.
• 6. ltlt?gtgt i ? ? Goal i ltlt?gtgt i ? (Closed
  formula-Blackburn et al. 2001)
• Informally whenever an agent attempts to do some
  action ?, he has the
• Goal to attempt to do that action and whenever an
  agent has the Goal to
• attempt to do the action ? he attempts to do the
  action ?.
• Frame Correspondance (IA-Frames)
• (s, s') ? B(i) and (s, t) ? Ratt(?, i) then there
  is a t' such that (s, t') ? Ratt(?, i)

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LIA Axioms (3)

• 7. AX ? ? ?i? Broersen (2003)/Castilho et
  al. (1999)
• (time/attempt interaction)
• SOUNDNESS THEOREM
• LIA multimodal logic is sound with respect to the
  class of frames being
• - Temporal trees,
• IA frames,
• B serial, transitive and Euclidean frames,
• G serial, transitive and Euclidean frames,
• BG-inclusive frames,
• NFB-frames,
• NLB-frames.

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Relativization of motivations

• Identifying some formal solutions for
  representing dependence relations between
• the motivational elements of a pragmatic plan.
  Each solution should correspond to a
• particular type of perstistence strategy of
  goals.
• Solution 1 Blind Agents
• Goali ?i ? ? ? Goali ?i ? ? ?i Goali
  ? (Strong-NoForgettingGoal)
• Herzig Longin (2004)
• Solution 2a Myopic Agents
• Bel i A (? B ?) ? Goali AF ? ? Reli (?, ?)
• Goal Relativization it is based on a
  motivational element, the future-
• directed goal that ? and on a doxastic element,
  the belief that f is necessary
• for ?.

A (? B ?) ?? E(?? ? ?)
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Formal results (1)

• Theorem 1 Attempt awareness
• ?i ? ? Beli ?i ?  
• Lemma 1 Fixpoint Lemma
• AF ? ? ? ? ?iAF ?
• Fixpoint Axiom of linear temporal logic
  (Segerberg)
• ? p ? (p v A ?p)

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Formal results (2)Goal Generation schema

• An agent has a pre-existing goal that ? and
  believes that f is necessary for ? therefore the
  agent has the goal that f (Von Wright 1972).
• Differently from Cohen Levesque (1990) and
  Meyer et al. (1999), in LIA the goal generation
  machinery is a provable property.
• SCHEMA 1 for myopic agent of type B
• Bel i A(? B ?) Belief about necessity of ? for
  ?
• Goali AF ?
• --------------------
• Goali AF ? ? Reli (?, ?)

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Formal results (3) Goal properties

• Definition 3 Achievement Goal
• A-Goali ? def Goali AF Beli ? ? ?Beli?
• Theorem 5a Persistence of Achievement Goals
  Blind Agent
• A-Goali ? ? ? Goali ?j ?? ?j (A-Goali
  ? ? Beli ?)
• A blind agent can abandon an achievement goal
  only if
• The agent believes that the goal has been
  achieved or
• The agent believes that it is impossible to
  achieve the goal.

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Formal results (4) Goal properties

• Proposition 2 Persistence for Achievement Goals
  The myopic agent
• A-Goali ? ? Reli (Beli ?,?) ? ? Goali ?j ?
  ?
• ?j (A-Goali ? ? ?Goali AF ? ? ? Beli
  ?E(?Beli ? ? ?) ? Beli ?))
• A blind agent can abandon a relativized
  achievement goal G1 only if
• The agent believes that the goal G1 has been
  achieved or
• The agent believes that it is impossible to
  achieve the goal G1 or
• The agent does not believe anymore that it
  necessary to achieve G1 in order to achieve G2
  (to which G1 is relativized) or
• The goal G2 to which G1 is relativized is
  abandoned.

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Formal results (5) Goal properties

• Lemma 2 Persistence of the belief about
  Necessity
• Beli ? E(?? ? ?) ? Beli?? ? ? Beli ?j ? ?
  ?j (Beli ? E(?? ? ?))
• Lemma 2 provides the formal base for generalizing
  the previous
• proposition 2 into Theorem 5b.

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Formal results (6) Goal properties

• Theorem 5b Persistence of Achievement Goals The
  myopic agent
• (Generalization of Proposition 2 trough Lemma 2)
• A-Goali ? ? Reli (Beli ?, ?) ?? Beli ?j ? ?
  
• ?j (A-Goali ? ? ?Goali AF ? ? Bel i?))
• A blind agent can abandon a relativized
  achievement goal G1 only if
• The agent believes that the goal G1 has been
  achieved or
• The agent believes that it is impossible to
  achieve the goal G1 or
• The goal G2 to which G1 is relativized is
  abandoned.

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Intentions (1)

• Definition 6 Present-directed Intention to do an
  action (Bratman 1987)
• PDI-to doi (?) def Goal i lt?gt i ?
• They are direct motivations to do the action
  when the time point of the
• planned action execution is attained (Bratman
  1987)
• Definition 7 Future-directed Intention to do an
  action (Bratman 1987)
• FDI-to doi (?) def A-GOALi lt?gt i ?
• They are elements of partial plans and play a
  role as inputs of further
• planning processes aimed at filling or
  modifying these partial plans
• (Bratman 1987)

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Intentions (2)

• Theorem 6
• FDI-to doi (?) ? Reli (Beli lt?gt i ?, ?) ?? Beli
  ?j ? ?
• ?j (FDI-to doi (?) ? ? Goali AF ? ? Beli lt?gt
  i ?)
• If the future-directed intention FDI-to doi (?)
  relativized to Goali AF ? does
• not persist at the next time point then at the
  next time point either
• agent i comes to believe that action ? is going
  to be executed next
• or agent i does not have anymore the Goali AF ?
  which was responsible
• for the generation of the future-directed
  intention.
• Theorem 7 Future-directed intention generation
• A-GOALi ? ? Beli A((Beli lt?gt i ?) B ?) ?
• FDI-to doi (?) ? Reli (Beli lt?gt i ?, ?)
• See previous Goal Generation Schema

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Intentions (3)

• Some additional properties of present-directed
  intentions. When
• agent i has the present-directed intention to do
  action ?
• he attempts to do ?
• he is aware of this attempt
• he has the goal to attempt to do ?
• he has the goal that the preconditions for
  executing action ? hold
• he cannot believe that the preconditions for
  executing action ? do not hold.
• Theorem 7 Present-directed intention properties
• PDI-to doi (?) ? ltlt?gtgt i ?
• PDI-to doi (?) ? Beli ltlt?gtgt i ?
• PDI-to doi (?) ? Goali ltlt?gtgt i ?
• PDI-to doi (?) ? Goali Pre (i, ?)
• PDI-to doi (?) ? ? Beli ? Pre (i, ?)

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Other issues (1)

• Distinction between instrumental goals (whose
  persistence depend on the
• persistence of superior goals in the plan) and
  terminal goals (unrelativized
• goals whose persistence do not depend on the
  persistence of superior
• goals in the plan).
• Relevant distinction for a theory of Motivational
  Altruism (Lorini
• Castelfranchi 2005) (different from Kantian
  Normative Altruism/desire-
• independent altruism, see also Searle 2000)
• A necessary condition for having that agent i is
  actually altruist towards
• agent j is the following agent i has the
  terminal goal that agent j achieves
• his goals (agent i has the terminal adoptive goal
  towards agent j)

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Other issues (2)

• Analysis of the notion of Self-realisable result
  (Searle 1983)
• A given state of affairs ? is a self-realisable
  result with respect to some agent i if
• and only if there is not an agent is action a
  such that it is necessary that agent i
• does a for guaranteeing that the state of
  affairs holds after having done a
• (Ex Tomorrow it will rain!)
• SELF-REALISABLE (f, i) def ? ia E(ai ? ? f)
  ?? ia A(ltagti T B f)

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Other issues (3)

• Definition and Properties of Intention THAT f
  (where f is some state of affairs or some other
  agents action).
• An agent can abandon the intention THAT f
  relativized to Goal AFi if
• either
• 1. he believes that it does not exist any of his
  actions that it is necessary for achievingthe
  result f (or he believes that f is
  self-realisable) or
• 2. he believes that f is actually holding or
• 3. he does not have anymore the Goali AF ? which
  was responsible for the generation of A-Goali f.