## In under and hour (30 min. or so), this extension to Able was
## written to solve the Gas problem taken from p. 14-15 in _The Think
## Aloud Method_, van Someren, M. W., Barnard, Y. F., & Sandberg, J. A.
## C., Academic Press: London.
## Granted, it is a simple problem.
## Frank E. Ritter, 4 Sept. 96

sp {kp*elaborate-space*boyle
   (state <s> ^problem-space kinematic-principles)
-->
   (<s> ^principle <k1> + &)
     (<k1> ^name boyle-law ^print-name |p1v1/t1=p2v2/t2|
	   ^pid b1 ^number-of-variables 6
	   ^variables <t1> + &, <p1> + &, <v1> + &, 
                      <t2> + &, <p2> + &, <v2> + &
	   ^first-variable <t1>  ^last-variable <v2>)
       (<t1> ^name temperature1 ^next-variable <p1>)
       (<p1> ^name pressure1 ^next-variable <v1>)
       (<v1> ^name volume1 ^next-variable <t2>)
       (<t2> ^name temperature2 ^next-variable <p2>)
       (<p2> ^name pressure2 ^next-variable <v2>)
       (<v2> ^name volume2 ^next-variable nil)}

sp {solve*elaborate*new-state*gas-problem
  (state <s> ^problem-space solve-kinematic
	     -^achieved
	     ^operator <o>)
  (<o> ^name fetch-problem ^problem-number gas)
  -->
  (<s> ^problem <pb> + > ^problem-name gas-problem-from-book
         ^problem-number gas + > ^achieved no +)
    (<pb> ^kinematic-variable <p1> + &, <t1> + &, <v1> + &,
                              <p2> + &, <t2> + &, <v2> + &
           ^situation standard ^desired <d>)
  (<d> ^variable <p2> ^number 1)
  (<t1> ^status known ^name temperature1 ^target no)
  (<p1> ^status known ^name pressure1  ^target no)
  (<v1> ^status known ^name volume1  ^target no)
  (<t2> ^status known ^name temperature2  ^target no)
  (<p2> ^status unknown ^name pressure2  ^target yes)
  (<v2> ^status known ^name volume2  ^target no)
}

sp {sk*fetch-problem*elaborate*main-get
   (state <s> ^problem-space solve-kinematic
	      ^operator <o>)
     (<o> ^name fetch-problem)
-->
   (<o> ^problem-number gas ^finished t)
     (tcl | makeprincipleswindow |)}