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text/paper_01/pre-paper.tex
... | ... | @@ -129,10 +129,10 @@ citecolor=blue, |
129 | 129 | \Acf{ASP} is a logic programming paradigm based on the \ac{SM} semantics of \acp{NP} that can be implemented using the latest advances in SAT solving technology. Unlike ProLog, \ac{ASP} is a truly declarative language that supports language constructs such as disjunction in the head of a clause, choice rules, and hard and weak constraints. |
130 | 130 | |
131 | 131 | \todo{references} |
132 | -The \ac{DS} is a key approach to extend logical representations with probabilistic reasoning. \Acp{PF} are the most basic \ac{DS} stochastic primitives and take the form of logical facts, $a$, labelled with probabilities, $p$, such as $\probfact{p}{a}$; Each \ac{PF} represents a boolean random variable that is true with probability $p$ and false with probability $\co{p} = 1 - p$. A (consistent) combination of the \acp{PF} defines a \acf{TC} $c = \set{\probfact{p}{a}, \ldots}$ such that | |
132 | +The \ac{DS} is a key approach to extend logical representations with probabilistic reasoning. \Acp{PF} are the most basic \ac{DS} stochastic primitives and take the form of logical facts, $a$, labelled with probabilities, $p$, such as $\probfact{p}{a}$; Each \ac{PF} represents a boolean random variable that is true with probability $p$ and false with probability $\co{p} = 1 - p$. A (consistent) combination of the \acp{PF} defines a \acf{TC} $t = \set{\probfact{p}{a}, \ldots}$ such that \franc{changed \acl{TC} $c$ to $t$ everywhere.} | |
133 | 133 | |
134 | 134 | \begin{equation} |
135 | - \pr{C = c} = \prod_{a\in c} p \prod_{a \not\in c} \co{p}. | |
135 | + \pr{T = t} = \prod_{a\in t} p \prod_{a \not\in t} \co{p}. | |
136 | 136 | \label{eq:prob.total.choice} |
137 | 137 | \end{equation} |
138 | 138 | |
... | ... | @@ -379,7 +379,7 @@ The diagram in \cref{fig:running.example} illustrates the problem of extending p |
379 | 379 | |
380 | 380 | Given an ASP specification, |
381 | 381 | \remark{{\bruno Introduce also the sets mentioned below}}{how?} |
382 | - we consider the \emph{atoms} $a \in \fml{A}$ and \emph{literals}, $z \in \fml{L}$, \emph{events} $e \in \fml{E} \iff e \subseteq \fml{L}$ and \emph{worlds} $w \in \fml{W}$ (consistent events), \emph{\aclp{TC} } $c \in \fml{C} \iff c = a \vee \neg a$ and \emph{\aclp{SM} } $s \in \fml{S}\subset\fml{W}$. | |
382 | + we consider the \emph{atoms} $a \in \fml{A}$ and \emph{literals}, $z \in \fml{L}$, \emph{events} $e \in \fml{E} \iff e \subseteq \fml{L}$ and \emph{worlds} $w \in \fml{W}$ (consistent events), \emph{\aclp{TC} } $t \in \fml{T} \iff t = a \vee \neg a$ and \emph{\aclp{SM} } $s \in \fml{S}\subset\fml{W}$. | |
383 | 383 | |
384 | 384 | Our path starts with a perspective of \aclp{SM} as playing a role similar to \emph{prime} factors. The \aclp{SM} of a specification are the irreducible events entailed from that specification and any event must be \replace{interpreted}{considered} under its relation with the \aclp{SM}. |
385 | 385 | |
... | ... | @@ -515,48 +515,48 @@ where $\indepclass$ denotes both the class of \emph{independent} events $e$ such |
515 | 515 | \item Normalization of the weights. |
516 | 516 | \end{enumerate} |
517 | 517 | |
518 | -The ``extension'' phase, traced by equations (\ref{eq:prob.total.choice}) and (\ref{eq:weight.tchoice} --- \ref{eq:weight.events}), starts with the weight (probability) of \aclp{TC}, $\pw{c} = \pr{C = c}$, expands it to \aclp{SM}, $\pw{s}$, and then, within the equivalence relation from \cref{eq:equiv.rel}, to (general) events, $\pw{e}$, including (consistent) worlds. | |
518 | +The ``extension'' phase, traced by equations (\ref{eq:prob.total.choice}) and (\ref{eq:weight.tchoice} --- \ref{eq:weight.events}), starts with the weight (probability) of \aclp{TC}, $\pw{t} = \pr{T = t}$, expands it to \aclp{SM}, $\pw{s}$, and then, within the equivalence relation from \cref{eq:equiv.rel}, to (general) events, $\pw{e}$, including (consistent) worlds. | |
519 | 519 | |
520 | 520 | \begin{description} |
521 | 521 | % |
522 | 522 | \item[Total Choices.] Using \eqref{eq:prob.total.choice}, this case is given by |
523 | 523 | \begin{equation} |
524 | - \pw{c} := \pr{C = c}= \prod_{a\in c} p \prod_{a \not\in c} \co{p} | |
524 | + \pw{t} := \pr{T = t}= \prod_{a\in t} p \prod_{a \not\in t} \co{p} | |
525 | 525 | \label{eq:weight.tchoice} |
526 | 526 | \end{equation} |
527 | 527 | % |
528 | - \item[Stable Models.] Each \acl{TC} $c$, together with the rules and the other facts of a specification, defines a set of \aclp{SM} associated with that choice, that \remark{we denote by $\tcgen{c}$}{put this in the introduction, where core concepts are presented}. | |
528 | + \item[Stable Models.] Each \acl{TC} $t$, together with the rules and the other facts of a specification, defines a set of \aclp{SM} associated with that choice, that \remark{we denote by $\tcgen{t}$}{put this in the introduction, where core concepts are presented}. | |
529 | 529 | |
530 | - Given a \acl{SM} $s \in \fml{S}$, a \acl{TC} $c$, and variables/values $\theta_{s,c} \in \intcc{0, 1}$, | |
530 | + Given a \acl{SM} $s \in \fml{S}$, a \acl{TC} $t$, and variables/values $\theta_{s,t} \in \intcc{0, 1}$, | |
531 | 531 | \begin{equation} |
532 | - \pw{s, c} := \begin{cases} | |
533 | - \theta_{s,c} & \text{if~} s \in \tcgen{c}\cr | |
532 | + \pw{s, t} := \begin{cases} | |
533 | + \theta_{s,t} & \text{if~} s \in \tcgen{t}\cr | |
534 | 534 | 0&\text{otherwise} |
535 | 535 | \end{cases} |
536 | 536 | \label{eq:weight.stablemodel} |
537 | 537 | \end{equation} |
538 | - such that $\sum_{s\in \tcgen{c}} \theta_{s,c} = 1$. | |
538 | + such that $\sum_{s\in \tcgen{t}} \theta_{s,t} = 1$. | |
539 | 539 | % |
540 | 540 | \item[Classes.] \label{item:class.cases} Each class is either the inconsistent class, $\inconsistent$, or is represented by some set of \aclp{SM}. |
541 | 541 | \begin{description} |
542 | 542 | \item[Inconsistent Class.] The inconsistent class contains events that are logically inconsistent, thus should never be observed: |
543 | 543 | \begin{equation} |
544 | - \pw{\inconsistent, c} := 0. | |
544 | + \pw{\inconsistent, t} := 0. | |
545 | 545 | \label{eq:weight.class.inconsistent} |
546 | 546 | \end{equation} |
547 | 547 | \item[Independent Class.] A world that neither contains nor is contained in a \acl{SM} describes a case that, according to the specification, shouldn't exist. So the respective weight is set to zero: |
548 | 548 | \begin{equation} |
549 | - \pw{\indepclass, c} := 0. | |
549 | + \pw{\indepclass, t} := 0. | |
550 | 550 | \label{eq:weight.class.independent} |
551 | 551 | \end{equation} |
552 | 552 | \item[Other Classes.] The extension must be constant within a class, its value should result from the elements in the \acl{SC}, and respect the assumption \ref{assumption:smodels.independence} (\aclp{SM} independence): |
553 | 553 | \begin{equation} |
554 | - \pw{\class{e}, c} := \sum_{k=1}^{n}\pw{s_k, c},~\text{if}~\stablecore{e} = \set{s_1, \ldots, s_n}. | |
554 | + \pw{\class{e}, t} := \sum_{k=1}^{n}\pw{s_k, t},~\text{if}~\stablecore{e} = \set{s_1, \ldots, s_n}. | |
555 | 555 | \label{eq:weight.class.other} |
556 | 556 | \end{equation} |
557 | 557 | and |
558 | 558 | \begin{equation} |
559 | - \pw{\class{e}} := \sum_{c \in \fml{C}} \pw{\class{e}, c}\pw{c}. | |
559 | + \pw{\class{e}} := \sum_{t \in \fml{T}} \pw{\class{e}, t}\pw{t}. | |
560 | 560 | \label{eq:weight.class.unconditional} |
561 | 561 | \end{equation} |
562 | 562 | \remark{}{Changed from $\prod$ to $\sum$ to represent ``either'' instead of ``both'' since the later is not consistent with the ``only one stable model at a time'' assumption.} |
... | ... | @@ -564,17 +564,17 @@ The ``extension'' phase, traced by equations (\ref{eq:prob.total.choice}) and (\ |
564 | 564 | % |
565 | 565 | \item[Events.] \label{item:event.cases} Each (general) event $e$ is in the class defined by its \acl{SC}, $\stablecore{e}$. So, we set: |
566 | 566 | \begin{equation} |
567 | - \pw{e, c} := \frac{\pw{\class{e}, c}}{\# \class{e}} . | |
567 | + \pw{e, t} := \frac{\pw{\class{e}, t}}{\# \class{e}} . | |
568 | 568 | \label{eq:weight.events} |
569 | 569 | \end{equation} |
570 | 570 | and |
571 | 571 | \begin{equation} |
572 | - \pw{e} := \sum_{c\in\fml{C}} \pw{e, c} \pw{c}. | |
572 | + \pw{e} := \sum_{t\in\fml{T}} \pw{e, t} \pw{t}. | |
573 | 573 | \label{eq:weight.events.unconditional} |
574 | 574 | \end{equation} |
575 | - % \remark{instead of that equation}{if we set $\pw{s,c} := \theta_{s,c}$ in equation \eqref{eq:weight.stablemodel} here we do: | |
575 | + % \remark{instead of that equation}{if we set $\pw{s,t} := \theta_{s,t}$ in equation \eqref{eq:weight.stablemodel} here we do: | |
576 | 576 | % $$ |
577 | - % \pw{e} := \sum_{c\in\fml{C}} \pw{e, c}\pw{c}. | |
577 | + % \pw{e} := \sum_{t\in\fml{T}} \pw{e, t}\pw{t}. | |
578 | 578 | % $$ |
579 | 579 | % By the way, this is the \emph{marginalization + bayes theorem} in statistics: |
580 | 580 | % $$ |
... | ... | @@ -585,13 +585,13 @@ The ``extension'' phase, traced by equations (\ref{eq:prob.total.choice}) and (\ |
585 | 585 | |
586 | 586 | % PARAMETERS FOR UNCERTAINTY |
587 | 587 | \begin{itemize} |
588 | - \item \todo{Remark that $\pw{\inconsistent, c} = 0$ is independent of the \acl{TC}.} | |
588 | + \item \todo{Remark that $\pw{\inconsistent, t} = 0$ is independent of the \acl{TC}.} | |
589 | 589 | \item Consider the event $bc$. Since $\class{bc} = \indepclass$, from \cref{eq:weight.class.independent} we get $\mu\at{bc} = 0$. |
590 | 590 | \item \todo{Remark that equation \eqref{eq:weight.events.unconditional}, together with observations, can be used to learn about the \emph{initial} probabilities of the atoms, in the specification.} |
591 | 591 | \end{itemize} |
592 | 592 | |
593 | 593 | |
594 | -The $\theta_{s,c}$ parameters in equation \eqref{eq:weight.stablemodel} express the \emph{specification's} lack of knowledge about the weight assignment, when a single \acl{TC} entails more than one \acl{SM}. In that case, how to distribute the respective weights? Our proposal to address this problem consists in assigning an unknown weight, $\theta_{s,c}$, conditional on the \acl{TC}, $c$, to each \acl{SM} $s$. This approach allows the expression of an unknown quantity and future estimation, given observed data. | |
594 | +The $\theta_{s,t}$ parameters in equation \eqref{eq:weight.stablemodel} express the \emph{specification's} lack of knowledge about the weight assignment, when a single \acl{TC} entails more than one \acl{SM}. In that case, how to distribute the respective weights? Our proposal to address this problem consists in assigning an unknown weight, $\theta_{s,t}$, conditional on the \acl{TC}, $t$, to each \acl{SM} $s$. This approach allows the expression of an unknown quantity and future estimation, given observed data. | |
595 | 595 | |
596 | 596 | % SUPERSET |
597 | 597 | Equation \eqref{eq:weight.class.other} results from conditional independence of \aclp{SM}. |
... | ... | @@ -608,14 +608,14 @@ We continue with the specification from Equation \eqref{eq:example.1}. |
608 | 608 | \item[\Aclp{TC}.] The \aclp{TC}, and respective \aclp{SM}, are |
609 | 609 | \begin{center} |
610 | 610 | \begin{tabular}{ll|r} |
611 | - \textbf{\Acl{TC}} & \textbf{\Aclp{SM}} & \textbf{$\pw{c}$}\ | |
611 | + \textbf{\Acl{TC}} & \textbf{\Aclp{SM}} & \textbf{$\pw{t}$}\ | |
612 | 612 | \hline |
613 | 613 | $a$ & $ab, ac$ & $0.3$\\ |
614 | 614 | $\co{a} = \neg a$ & $\co{a}$ & $\co{0.3} = 0.7$ |
615 | 615 | \end{tabular} |
616 | 616 | \end{center} |
617 | 617 | % |
618 | - \item[\Aclp{SM}.] The $\theta_{s,c}$ parameters in this example are | |
618 | + \item[\Aclp{SM}.] The $\theta_{s,t}$ parameters in this example are | |
619 | 619 | $$ |
620 | 620 | \theta_{ab,\co{a}} = \theta_{ac,\co{a}} = \theta_{\co{a}, a} = 0 |
621 | 621 | $$ |
... | ... | @@ -628,9 +628,9 @@ We continue with the specification from Equation \eqref{eq:example.1}. |
628 | 628 | \begin{equation*} |
629 | 629 | \begin{array}{l|ll|r} |
630 | 630 | \stablecore{e} |
631 | - & \pw{s_k, c= \co{a}} | |
632 | - & \pw{s_k, c= a} | |
633 | - & \pw{\class{e}}=\sum_{c}\pw{\class{e},c}\pw{c} | |
631 | + & \pw{s_k, t= \co{a}} | |
632 | + & \pw{s_k, t= a} | |
633 | + & \pw{\class{e}}=\sum_{t}\pw{\class{e},t}\pw{t} | |
634 | 634 | \\ |
635 | 635 | \hline |
636 | 636 | \co{a} |
... | ... | @@ -675,16 +675,19 @@ We continue with the specification from Equation \eqref{eq:example.1}. |
675 | 675 | & 1 |
676 | 676 | \end{array} |
677 | 677 | \end{equation*} |
678 | - \item[Normalization.] To get a weight that sums up to one, we compute the \emph{normalization factor}. Since $\pw{\cdot}$ is constant on classes we have | |
678 | + \item[Normalization.] To get a weight that sums up to one, we compute the \emph{normalization factor}. Since $\pw{\cdot}$ is constant on classes, | |
679 | 679 | \begin{equation*} |
680 | 680 | Z := \sum_{e\in\fml{E}} \pw{e} |
681 | - = \sum_{\class{e} \in\fml{E}/\sim} \frac{\pw{\class{e}}}{\#\class{e}}, | |
681 | + = \sum_{\class{e} \in\class{\fml{E}}} \frac{\pw{\class{e}}}{\#\class{e}}, | |
682 | 682 | \end{equation*} |
683 | - that divides the weight function into a normalized weight: | |
683 | + that divides the weight function into a normalized weight | |
684 | 684 | \begin{equation*} |
685 | 685 | \pr{e} := \frac{\pw{e}}{Z}. |
686 | 686 | \end{equation*} |
687 | - | |
687 | + such that | |
688 | + $$ | |
689 | + \sum_{e \in \fml{E}} \pr{e} = 1. | |
690 | + $$ | |
688 | 691 | For the SBF example, |
689 | 692 | \begin{equation*} |
690 | 693 | \begin{array}{lr|r|rr} |
... | ... | @@ -969,7 +972,7 @@ Considering the probabilities given in \cref{Figure_Alarm} we obtain the followi |
969 | 972 | \item The physical system might have \emph{latent} variables, possibly also represented in the specification. These variables are never observed, so observations should be concentrated \emph{somewhere else}. |
970 | 973 | \item Comment on the possibility of extending equation \eqref{eq:weight.events.unconditional} with parameters expressing further uncertainties, enabling a tuning of the model's \aclp{TC}, given observations. |
971 | 974 | \begin{equation*} |
972 | - \pw{e} := \sum_{c\in\fml{C}} \pw{e, c}\theta_c. | |
975 | + \pw{e} := \sum_{c\in\fml{T}} \pw{e, c}\theta_c. | |
973 | 976 | \end{equation*} |
974 | 977 | \end{itemize} |
975 | 978 | ... | ... |