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# Utilizing Time as a part of Weaving machine.

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Description
Previous Hockey Player. Transient idea
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﻿Utilizing Time as a part of Loom Thomas A. Russ USC Information Sciences Institute

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Outline Time Representation Basic Assertions Basic Queries Persistence Time and the Classifier Advanced Examples

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Agent and World Time World Time Records Domain Facts Agent Time Records Knowledge Base Changes

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Time Representation Definite Times Integers Time Strings "10/28/94 11:33" Anchored to Calendar Common Lisp all inclusive time Points Are Basic Units Intervals Are Derived "Property" Interpretation of Intervals

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Properties and Events Properties True over all subintervals "The house is red" Events True just over the whole interim "John ran totally around the track."

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Basic Assertions Transitions Only ( :starts at time-point affirmation) ( :closes at time-point declaration) Strong Temporal Assertion Before :starts at, statement is false. After :starts at, attestation is valid.

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Basic Assertions (:not (P x)) (P x) Time1 (tell (:starts at Time1 (P x))) (:not (P x)) (P x) (:not (P x)) Time2 Time1 (tell (:closes at Time2 (P x)))

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Basic Queries—Transitions: (ask (:closes at t1 (P x)))

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Basic Queries—States Transitions: (ask (:closes at t1 (P x))) States: (ask (:holds-at t1 (P x)))

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Basic Queries—States Problem Transitions: (ask (:closes at t1 (P x))) States: (ask (:holds-at t1 (P x))) But this can be not well characterized (P x) t1

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Basic Queries—States Solution Introduce Directional Operators (ask ( :holds-before t1 (P x))) (ask ( :holds-after t1 (P x))) Yields all around characterized comes about: (P x) t1 :holds-before ==> t :holds-after ==> nil

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Non-Transitional Assertions Persistence Only ( :holds-after time-point declaration) ( :holds-before time-point affirmation) Weak Temporal Assertion Before :holds-after, attestation can be valid or false. After :holds-some time recently, affirmation can be valid or false. :holds-at is the mix of :holds-before and :holds-after The attestation is genuine both previously, then after the fact a :holds-at

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Persistence Assertions ?? (P x) Time1 (tell (:holds-after Time1 (P x))) ?? (P x) Time1 Time2 (tell (:holds-after Time2 (P x))) (P x) Time1 Time2 Time3 (tell (:holds-before Time3 (P x)))

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Temporal Operator Truth Table (P x) :starts at :holds-after :holds-at :holds-before :closures at t1 t2 t3 t nil nil t t nil t nil t t nil nil t

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Changes to Classifier Is Time Sensitive Temporal data in the ABox influences characterization Definitions Are Time Invariant TBox definitions hold over the whole course of events

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Bachelor Example (defconcept Married :qualities :fleeting) (defconcept Bachelor :is (:and Male (:not Married))) (tell (Male p1) (:starts at t1(Married p1))) (Male p1) (:not (Married p1)) (Married p1) t1 (Bachelor p1) t1

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Widow Example (defconcept Dead :attributes :worldly) (defrelation husband :is (:and mate (:range Male)) :qualities :transient) (defconcept dowager :is (:and Female (:some husband Dead)))

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Widow Assertions (tellm (Female Mary) (Male John)) (tellm (:starts at "1/1/90" (life partner Mary John)) (:starts at "1/1/94" (Dead John))) (Male John) (Female Mary) (mate Mary John) 1/1/90 (Dead John) 1/1/94

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Widow Derivation (tellm (Female Mary) (Male John)) (tellm (:starts at "1/1/90" (companion Mary John)) (:starts at "1/1/94" (Dead John))) (Male John) (Female Mary) (life partner Mary John) 1/1/90 (Dead John) 1/1/94 (Widow Mary) 1/1/94

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Widow Queries (mate Mary John) 1/1/90 (Dead John) 1/1/94 (Widow Mary) 1/1/94 (recover ?x (:holds-at "10/28/94" (dowager ?x))) => (|i|Mary) (recover ?x (:starts at ?x (Widow Mary))) => (2966400000) ; = "1/1/94 00:00:00"

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Former Hockey Player (defconcept previous hockey-player :is (:and individual (:fulfills (?p) (:for-a few (?t) (:and (past ?t) (:closes at ?t (hockey-player ?p )))))))

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Former Hockey Player (defconcept previous hockey-player :is (:and individual (:fulfills (?p) (:for-a few (?t) (:and ( past ?t) (:closes at ?t (hockey-player ?p ))))))) Temporal idea " past " obliges matches for ?t to happen before the time this definition is fulfilled. A previous hockey player is "somebody who stopped to be a hockey player at some point before."

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Former Hockey Player Temporal Clause Temporal connection to the idea "hockey-player" built up. (defconcept previous hockey-player :is (:and individual (:fulfills (?p) (:for-a few (?t) (:and (past ?t) (:closes at ?t (hockey-player ?p )))))))

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Former Hockey Player Assertion and Queries (tellm (Person Fred)) (tellm (:closes at "1/1/90" (hockey-player Fred))) (ask (:holds-at "1/1/88" (hockey-player Fred))) => T (ask (:holds-at "1/1/88" (previous hockey-player Fred))) => NIL (ask (:holds-at "1/1/94" (hockey-player Fred))) => NIL (ask (:holds-at "1/1/94" (previous hockey-player Fred))) => T

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Summary World and Agent Time Supported Definite, Calendar-Anchored Time ABox Supports Temporal Assertions Inference Is Time Sensitive

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