From: AAAI-82 Proceedings. Copyright ©1982, AAAI (www.aaai.org). All rights reserved.
SPATIALANDTEMPORAL
REASONING IN GEOLOGIC MAP INTERPRETATION
Reid G. Simmons
l’hc Artificial lntclligcncc
Laboratory
Massachusetts
Institute of’I’cchnology
Cambridge,
MA 02139
11
A BS’I’RACT
In this paper.
scvcral
problem
known
dcGlcd
both
WC dcscribc
Al tcchniqucs
a way of extending
to attack a class of problems
as geologic
and an abstract
map
intcrprctntion.
m!)dcl of clcmcntllry
local and global
reasoning
and combining
cxcmplificd
to achicvc
geologic
rcprcscnting
a
identifying
with
rcconsn-uct
WC USC both
geology. combined
tcchniqucs
In
by a
the system’s
MAP
map
a vertical
the
intcrprctation,
formed that region.
one
cross-section
various
a plausible
IN’l‘l’lil’liE1‘A’I‘ION
is given
of a region,
rock
formations.
scqucnce
of geologic
a diagram
plus
l‘he
a legend
is to
problem
events which could have
A simple map cxamplc
is shown in Figure
1.
cxpcrtise.
In particular,
global
a new technique
inconsistcncics
scqucncc
of “instructions”.
and abstract
Imagining
by causally
simulating
cl
El
q
a
makes USCof both our detailed
models of the world.
I
A rcccnt
trend
lNI’l~Ol~U@l’lON
in cxpcrt
systems
which
reason
domain,
rather
than
model”
versus
systems
rcscarch
from descriptions
from the surface
“cinpirical
Typically,
this involves
which
undcrly
creating
infcrcnccs
about
how the processes
has been
toward
processes
in the
of causnl
cffccts.
association”
proccsscs
interact
allows us to find
called im@Jing
in our hypothcscs
‘I’his is the “causal
distinction
a dctailcd
the domain.
prcscntcd
model
A geologist
must
the world,
through
L+ith CHICanother.
bcforc
the shalt.
One
complex
amount
\shich
problem
with
such
to allow the rclcvant
of time.
abstract
Hcncc.
models
infcrcnccs
rcprcscntntions
or compress
they
arc often
too
and methods
the surface
of reasoning
for much
‘I’hc full model may bc used when thcsc less
problem
sol\ ing process.
methods
problem
solving process as a whole.
but
that
should
occur
infrcqucntly
rcscarch
cxplorcs
schist
dctailcd
and an abstract
problem
from geology
outline
tbc types
model
of the domain,
both
a
using as a tcstbcd
a
knowlcdgc
nccdcd
to rcprcscnt
reason about the geologic cm~ironmcnt.
We illustmtc
a detailed
model
and a more abstract
employing
diagrams.
of geologic
to solve the problem.
called imagining.
scqucnce
with particular
emphasis
and
(i.c. forced
‘I’hc geologist would
also intruded
crcatcd
from
arc dcpositcd
existing
A combination
to bring
rock
mctrrmorphism
gotten
‘1’0 dctcrmine
the geologist
from above onto
on top of the schist.
by
the
occurs
of
rrplifi
to the surface.
of
buried
so somehow
to the surface
of the proccsscs
the schist
process
in rocks
occurs on the surface.
from the depths
in
would
to be
and erosion
‘Hius. the final
of cvcnts is:
schist
and shale
model
nccdcd
Solving
introductory
the effects of a
inconsistcncics
that, since
through
them.
appcarcd.
1. Metamorphism
of schist
2. LJplift and erosion of schist
3. Deposition
of shdc on schist
4. Intrusion of mafir igneous through
on a I&W technique
allows one to “visualize”
and detects any global
suflicc
the USCof both
WC also discuss the types of reasoning
Imagining
of proccsscs.
proccsscs
upon.
scqucncc
In this paper, we
known as map intcrprctation.
of geologic
from
through
deposits
Howcvcr,
must have
dcpositcd
the issues of reasoning
intruded
deep in the IGIrth and deposition
the
in the
would
‘lhis
was
mctnmorphism.
by noting
’ intruded
It
of the F:nrth. the sh:~lc was dcpositcd
‘I’hc schist
of the
Prohlctn
this problem
and the sMc
the schist
infer that, since scdimcntar!’
ro bc mndc in a reasonable
derail arc very useful
dct;lilcd
fitil.
is that
schist
‘l’hus the sh;dc and the schist wcrc both in place
the mafic igneous
what order
jr,!::
’ I,‘,
to infer that the mafic igneous
USC the same reasoning
and how they
shale
Rlap lntcrprctation
crosses the schist,*
igneous
--
the schist and IICIICCis younger.
its way through)
support
Ccologic
would approach
UK m;~fic igneous
in [2].
of the physical
‘I’his model
affect
Fig. 1. Simple
ndic
solvable
in that
the map intcrprctation
geology
courses.
with an clcmcntary
problem
This indicates
knowledge
is typically
that
of geology,
taught
the problem
togcthcr
in
is
with
sequence.
Ihis work was supported in part by a Graduate Fellowship from
the National Scicncc Foundation.
* Our geologic knowledge includes the facts that schist is a merumorphic rock. mafic
qycous is rpneolrs. and shalt IS a sedrmenruty deposit.
152
some
common
clcmcntary
sense
geologic
physical
details of a complete
continuous
cn\iro&cnt.
cotnplcx,
is nccdcd
model of geology
the other hand, the domain
about
knowlcdgc.
knowlcdgc
11~2 fact
mcans
and
their
bccausc
and the USCof dctrlilcd and abstract
cffccts
gologic
proccsscs
an
process
of erosion
and
drawing
a horizontal
on
is both bounded
choice for studying
can be readily inferred
A key tcchniquc
On
one must reason
interacting
WC feel that since the domain
it is a good problem
formations
only
air.
mod&.
1’Yf’l’S OF KNOWI .HXl’
abo\c
cxamplc:
knowlcdgc
temporal
knowledge
diagrams
as abstrilctions
A.
Gcolocic
the nature
process
knowledge
forms
the diagram
proccsscs
processes,
(Figure
the line whcrc it cuts through
have spatial
metamorphic
rock”, and knowlcdgc
us to infer.
for cxamplc,
cnvironmcnt.
in the geologic
model.
it proves
simultaneously.
‘I’hat is, to ascertain
to bc niorc
of our
erosion
about
process.
would
how proccsscs
Cxilmplc,
approach
knowlcdgc
those proccsscs
uplift
bccausc
and
hail
2. Diqg-aiimatic
IXccls
of Erosion
‘Ihis diagram
For
The
happen
Process ‘lhcory
wing-cdgc
[4]
and
us to rcprcscnt
and knowlcdgc
about
underlying
structure
topological
sub-system
how
transformation
rcprcscntation
of [I].
facility
has hccn
for the diagram
This rcprcscntation
inferences.
The
implcmcntcd.
is based
facilitates
inrcrfacc
6ctwccn
of terms such as fnccs. edges. sidcdncss
above. Ieft-ctJ and adjacency
to reason
about
In the synthetic
s~trr/zc~ic and a~l~~ric mode.
tllc causes,
simulating
cn\ironmcnt.
the geologic
proccsscs
In the analytic
analyzing
the diffcrcncc
cxistcnce
of a geologic
proccsscs
mode we reason
to dctcrmine
mode
bctwccn
in both
their effects
we reason
from
the
relations
bctwccn
diagram,
as draiving
which
account
for
T\‘l’l3
--
of
geologic
arc a number
cvcnts.
those
One way to view this problem
geologic
an attribute
- those
inrcrval.
of diffcrcnt
whose
problems
example,
proccsscs.
of an object
in creating
WC need
scqucnces
a mechanism
lalucs
and to reason
do not
change
about
over
that the Qualitative
Process
A.
is as a standard
Scenario
geologic
proccsscs).
forward starch
from the cffccts of processes
a particular
scmnrio
on these
pnttcrn
‘l’hcory,
with its
caused that pnttcrjl.
and a set of scqucnccs
First
they abstract
of fomlntions.
knowlcdgc,
cntiry
diagrams
l)iagrams
Second.
diagrams
position,
arc used
away irrclcvant
unlike
arc spatially
in space is directly
ndjnccncy,
<rock>
and
as an abstraction
facilitate spatial infcrcnccs
rclatcd
other
rcprcscntalions
organi/.cd,
sccnsrio
is ~1pair consisting
fcaturcs
approach.
of an
such
The
scqucncc
of cvcnts
pnttcrn’s
occurrcncc.
prcscntation
as
processes).
153
rcprcscnt
bctwccn
intcrprctations.
i1
backwards
proccs5 wc call
of a diagrammatic
which could have
in solving the cxamplc
in Figure 1
twice:
igneous
<rock>
‘I’hc patterns
of the same
in the diagram.
of geologic
to be
it~lcrprctaliorr
igwous
boundaries
structure
that is. the position
to its position
orientation
of the
for two reasons.
dctiiils, such its internal
WC have
clear in this
WC reason
called itrterpwm~iotts
l;or cxamplc,
WC used the following
tractable,
to their causes using
A scenario
ttlalcltittg.
research
Knowledge
In this system,
_rcologic model.
it bccomcs
is not a plausible
pallcm
Dinrramtnatic
starch.
and operators
M:itcliing
In order to make the problem
enduring
idea of a hislor~~, is a step in the right direction.
C.
the
for
We alsl) need to formalize what causes
to change
WC have not yet done substantial
but we bclicvc
(i.e. all possible
view that unconstrained
For
rotating
01; RI:ASONING
’
an initial st,ltc of the Morld (c.g. the “void”).
l‘cmr>oral KnowlcdPc
‘I‘hcre arc also
a line,
or merging two facts.
IV
applied
topics,
such
the
diffcrcnces.
R
them (e.g.
relations (c.g. which lines make up a face,
commands,
cffccts,
to hypothcsizc
could
transformation
from
diagram
on the
the
two situations
process
a
on the
gcomctric
and the rest of the system is based on a small vocabulary
which face is on the orhcr side of an cdgc and a face).
temporal
to
the
directly.
Fig.
011 the
interact.
erosion
it cnablcs
proccsscs
WC
is a
interact.
WC need
artributcs
cfficicnt
it than it is to rci1son about
that would allow
WC intend to use the Qualitative
as the basis
composing
the
out than the
of
such as “schist
about proccsscs
whi)t cffcct
2 of the
solving
knowledge
WC also need to rcprcscnt
in step
Iherc
cffccts,
can bc more easily carried
and “view”
2) by
critsing all fices
the basis of the geologic
the problem
basic geologic
will need to reprcscnt
quali~ti~c
in a dingr;un
primarily
proccsscs.
of
of the geologic model.
which is used throughout
insLlncc.
of geologic
of cvcnts. and knowledge
infcrcnccs
of geologic
transform
the
proccsscs
the cffccts
For instrmcc, the
Process KnowledPc
Geologic
model,
about
to crcatc scqucnccs
in solving
is to rcprcscnt
line at the Icvci of the erosion.
transformations
corresponding
USED
basic types of knowlcdgc
the diagram.
transfomlations.
can bc visunlizcd
l~ccausc geologic
the cffccts
WC have used three
in this rcscarch
as diagrammatic
which arc above the line, and erasing
the USCof imagining
diagrammatic
I11
by “viewing”
of the
need not bc rcprcscntcd.
is f;lirly complex
proccsscs
that
that many
Note
language
intruded
local cffccts of proccsscs
two or three formations.
\vhich
is a possible
I3ch
that
through
pattern
scenarios
(diagrams)
the <rock>
and involve the
An itz/crmVnliot~
CaUSiil cxpl,ination
may
affccr
ha\~
scvcral
a translation
to the causal
language
is a
for the
plausible
from
the
(geologic
Ily matching
combining
purport
scenario
the local
to explain
scqucnccs
might
longer
for the occurrence
thcrc is no c\idcncc
uplift
and
the
a method
know that part of the schist
width
the
amount)
than the mcasurcd
Second,
proccsscs
might
of the processes
C.
types
If the imagincr
this situation.
An outgrowth
in@ncr
(a diagram),
simulates
cnvironmcnt
which is then compared
Although
The imagincr
the
imagincr
prohlcm
cncountcrcd.
the imagincr
actually
produced
process
should
mcntioncd
the search
This cxplnnation
why
to
intcrprctation
suffcicntly
model
to
reasoning
dctcct
both
outiincd
bc
intcrprctation
in the prcyious
simulated
involves
diagrammatic
“deposit
section.
models.
If
Imagining
of the
from
instnncc,
rock, and the diagram
imagincr
must
geologic
proccsscs.
scqucnce
is qualitative,
the diagrammatic
the
both
would
the
transformations.
correct
to simulate
“deposit
paramctcrs
In addition.
if the imagincr
A on IY the imngincr
Mpidth of A, at least within
mcasurcmcnts
taken
some dcfinitc
from the diagram,
and combining
cxcmplificd
several
by the map
WC have used both a dct;lilcd ahd an abstract
geology,
combined
with both local and global
imagining
by causally
allows us to find global inconsistencies
simulating
a scqucncc
makes USCof both our dctailcd
of “instructions”.
and abstract
models of the
1 would
was
Randy
Davis
and Chuck
for his guidance
Rich
for their
and
valuable
and comments.
these
for
Computer
Davis, Randall - “Expert Systems: Mhcre arc WC and where do
wc go from hcrc,” AAAl Mac;lyinc, Summer 1982.
DcKlccr, John11 - “Qualitntivc and Quantitative
Classical Mechanics,” M II’ AI-‘1X-352, 1975.
of the
Knowledge
in
in the input
to do
Forbus. Kcnncth
11. - “Qualitative
Reasoning about Physical
Proccsscs,” in Proc. lJCi11 7. \‘ancouvcr, Canada. August, 1981.
parameters
is to produce
range.
Forbus
to see if A is
to XC if B is
arc needed
a final
Ncwcll, Allen and Simon. H.A. - “GPS, A Program
Simul;itcs II~llllilll ~l’lli~UgllL,” in Computers
& Thourzht,
Fcigcnbaurn
and Feldman, 1963.
hnvc to know the
‘1%~ imngincr
plus knowlcdgc
Ken
hlodclling
11aumgart,
Bruce - “Gcomctric
Vision,” Stanford AIM 249, October 1974.
and
process
For cxan~plc. in order
would
Iikc to thank
and
processes
the parnmctcrs
of the processes
which is similar to the goal diagram.
a way of cxtcnding
a class of problems
process can
geologic
geologic
bc checked
to infer
but quantitative
CONCI .LJSION
in accordance
geologic
if a geologic
if the
The description
must bc approximately
diagram
bi: able
of
analysis
the state
on the surface.*
The
‘I‘his is mcuns-end
world.
inconsistencies
A on IY’, the geologic model would bc chcckcd
a sedimentary
about
the cffcct
This imagining
of
diagrams
of
11crccting
infcrcnccs
For
have
of the
thnt process and the state
types
works by transforming
diagrammatic
would
in terms
techniques.
In particular,
consists of the process which
bctwccn
problem.
in our hypothcscs
above.
the
continue
of processes
we
The
context.
to attack
of clcmcntary
supervision.
‘Ihc imagincr
not
that differcncc.
WC have dcscribcd
suggestions
with
or eliminating
AI tcchniqucs
by using a
311 CXplilll~tiOll
up to that process.
by simul~ring
or scqucncc
for
to fill the gap.
two states, and from that one can reason
to
cnvironmcnt.
and the diffcrcncc
in order to simulntc
suffice
of cvcnts
bctwccn
process
it could
the state nccdcd
indicarcs
of the scqucncc,
to the current
it returns
could not simulate.
which would bc ncedcd
imagining.
if each process
continue,
bctwccn
state of the cnviromncnt,*
imngincr
V
problem.
can bc npplicd
cannot
a “gap”
some scqucncc
The
WC noted thilt uncorrs,rcrir&
constrains
must dctcrminc
vicwcd as an opcmtor.
unknown
a final
with the gl>al cnvironmcnt
in this domain,
avoid the combinatorics
proccsscs.
in turn, producing
for\+nrd search is not practical
operators.
dctccts
[5] used in a restricted
[3]. imagining
of geologic
each of the proccsscs
of plausible
sonic
a goal stntc which is the final
and a scqucncc
scc if they qual itativcly match.
scqucncc
(by
width in the diagram.
diffcrcncc
minimizing
to handle
iwngirrirrg
of the notion of twrCorritlg
takes as input an initial cnvironmcnt,
cnvironmcnt
called
away (in step 2), the
was greater
to occur and the actual
need to hlpothcsilc
is ncedcd.
\vhich
a ncb technique
1,
Gap Filling
sonic process
of
Imagining
We arc dcvcloping
was Lltcr crodcd
formation
from Figure
and since we also
of
has removed
both
deposit,
no
For instance,
the erosion
of the
For instance,
of the schist
original
‘1’0 dctcct
of global reasoning
thcsc paramctcrs.
the width
these
(i.e. the diagram).
bccausc
to dctcrrninc
WC can mcasurc
First,
consistency.
schist.
processes
which
However,
1 for the occurrence
of the schist,
covcrcd
scqucnccs
for two reasons.
of some physical
record
in Figure
erosion
once
inconsistcncics,
B.
was formed.
does not iml~ly global
and
the diagram
how the region
exist in the geologic
whatc\er
throughout
WC gcncmtc
not be valid cxplaniltions
local consistency
evidence
patterns
interpretations,
uses
that
cds.
of geologic
* as would have occurred if WEhad not
in Figure 1.
+ The use of diagrams is not intnnsx to the concept of imagining. which merely
unplics causal smlulatlon of a scqucncc of “instructions”. ‘lhc unagmcr could work on
the pcolog~ model alone.
154
the presence of the uplift and erosion