drools

Geoffrey De Smet

Drools Planner in a nutshell

Agenda

Use casesBin packingWhat is NP complete?

Employee shift rosteringHard and soft constraints

Patient admission scheduleHow many possible solutions?

Is there much space to optimize?

Use cases

What are planning problems?

Hard constraint implementation

// a nurse can only work one shift per dayrule "oneShiftPerDay" when $left : EmployeeAssignment( $employee : employee, $shiftDate : shiftDate, $leftId : id ); $right : EmployeeAssignment( employee == $employee, shiftDate == $shiftDate, id > $leftId); then // Lower the hard score with a weight ...end

Soft constraint implementation

rule "dayOffRequest" when $dayOffRequest : DayOffRequest( $employee : employee, $shiftDate : shiftDate, $weight : weight ); $employeeAssignment : EmployeeAssignment( employee == $employee, shiftDate == $shiftDate ); then // Lower the soft score with the weight $weight ...end

Patient admission schedule

Hard constraintsNo 2 patients in same bed in same nightRoom gender limitationDepartment minimum or maximum agePatient requires specific room equipment(s)Soft constraintsPatient prefers maximum room sizeDepartment specializationRoom specializationPatient prefers specific room equipment(s)

Needle in a haystack

How many possible solutions?310 bedsin 105 roomsin 4 departments84 nights2750 patients (admissions)Numbers from a real dataset

Needle in a haystack

How many possible solutions?310 bedsin 105 roomsin 4 departments84 nights2750 patients (admissions)> books in British Museum?40 000 printed books

Source: wikipedia

Needle in a haystack

How many possible solutions?310 bedsin 105 roomsin 4 departments84 nights2750 patients (admissions)> humans?7000000000 humans

Source: NASA (wikipedia)

Needle in a haystack

How many possible solutions?310 bedsin 105 roomsin 4 departments84 nights2750 patients (admissions)> minimum atoms in the observable universe?10^80

Source: NASA and ESA (wikipedia)

Needle in a haystack

How many possible solutions?310 bedsin 105 roomsin 4 departments84 nights2750 patients (admissions)> atoms in the universe
if every atom is a universe
of atoms?(10^80)^80 = 10^6400

Source: NASA and ESA (wikipedia)

Needle in a haystack

How many possible solutions?310 bedsin 105 roomsin 4 departments84 nights2750 patients (admissions)A little over 10^6851

Do the math

1 patient310 beds310 ways to schedule 1 patient2 patients310 * 310 = 961003 patients310 * 310 * 310 = 297910002750 patients310 * 310 * ... * 310310^2750= a little over 10^6851

A little over 10^6851

17565400009613647714189309909847019528176031676612802408947467896773536824694320253771058944295328388965847321421820520338269384218763243353186553203291774156243401969717704429199723195574019731357439221586010900901318775661618988149185744289903563474940721372704649669447515706252843900344472960295273324597346780837674886972275338744554737771986776337765496773882810395955542351928331414378439283405132892358744224215499792287586474426914111457027335258269167103194692790665217766902628732489519488236496931246157419949856522543510386164584826962224171420152255658502323853504643497053252922727924406406179159327025274968691052425818270121710670552641837503435108794481961062422002729288737980404185875233912428178009558605680683578864680145557998942327371019832139824665975180911386722774004539981342785523851686636374432671601485496423110930175953308580416767966832068095365964656939583089443708945844323888227816296382464122209980716936990539499472027590738400791514217875461942733015467480308665074008529461146577114465977072581447925882122906827160570007228017056499674188148507908716786164922536467490587163626945689452927061532150637454615233641645612791027410608416476380642469085143980464067453971429400369608313929289399595696359958354101721624055729520838609453039985592726289376243856941429063767903919977138724432513602703448146045970566585076809576476984036923221553270878279574239866657156729051295085970100212856025787345034666683590797377984104207041334053480226788236770435009014979334517769826461063281178894554527012859966520606253098788699367180806367012372895824963357992764969799123361044456461687410981522493093316910464937089299655880447014074876397812210684054337706530175130912335567383560436635091489083375525519539844805718811296858076507685112192499405286337668107046095023999871224655107877174220679360212410573001491104381221662138764756898834588381340410892158544837200229008533930816794663631470201197595487045022087615873490295940409113638894083753062801416644858

A little over 10^6851

70757942487218045035508810158461046502812782292385633846174494690914238485407798379765738528402484632449685642401410897637632172694954465509230907381501728706686840208173164426348468614134650930610728341876292346711310677332648553951422991989751468506508069513397904821612697383659788320905691994864296149528670873271380180066507702490525594196383327289726362280241278856579591895744202499646581373849829964867870738964842426372580420928473929652466453066089306581572745139056256181505240205578741292314133858985615181677968313683876880079649763914095651402272047776108451445066888366968448972791816669030945790810396895725248399188822034667566483522327685006195080178525107491255245054238976705620547582329759857450557583834141364747838395082871684183199560673441708538602779816347949276957201268066627372831370768073558934679410276824283049183299518869516908654179971718550810202675628457097617280232889096038128616543128200089047813223519902714196694639844273986565523012106816309974964021700560537928432528631741787455155275823033005847637107210747721372066369346754152090839849611389908167353907349234368276522287410730637555342957452428266968002573227849933691449063418286501311036314048960528249465982665132492491072491788618403253474529440348798670244615185355092357283764936387607076234181916670755269421546530337284689838773122323053171794271444358533638806848969871884168582847613016398013006633016140503743175611255484273419291435502775849577615159921009571496639402549077872124227731739936370100132762333353473908080215719004335487157010620020523763648856692728699459471603410776592535816520745995861336577877431293776796124264697049418795186010546056975226424227455446011031581123438684685838655333776830823720356749120051129394691394743488410658613543537795455760655157849602214428915084056181314465895075924498263846040474495622654552157933867572542745838370889391243702358459244386561081479905545570084491443709439642235090455604548030317754849613813010298858282615659336373785985294

A little over 10^6851

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A little over 10^6851

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The search space is big!Compare with WWW size 22020000000 pagesEach possible solution2750 patients scheduled into 310 bedsStill need to calculate the score! => Drools Expert

Is there much room to optimize?

Yes

Optimization = less polution,
less costs or better service

more CPU power

better
algorithm

First fit decreasing algorithm (>= humans)

Summary

Summary

Drools Planner solves planning problems

Adding constraints is easy and scalable

Switching/combining algorithms is easy

Q & A

Questions?Useful linksWebsitehttp://www.jboss.org/drools/Reference manualhttp://www.jboss.org/drools/documentation.htmlBloghttp://blog.athico.com/Mailing lists (forum interface through nabble.com)http://www.jboss.org/drools/lists.html

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