wkh sdqho olwhudwxuh/ ydulrxv vwurqj dvvxpswlrqv lpsrvhg uhqghu lw xqqhfhvvdu| wr hvwlpdwh
KDF hvwlpdwruv1 Lq wkh uhodwhg olwhudwxuh/ Nlhihu +4<;3,/ dqg Duhoodqr +4<;:, duh qrw gluhfwo|
frqfhuqhg zlwk wkh KDF exw gr wrxfk rq d qxpehu ri uhodwhg lvvxhv rq fryduldqfh hvwlpdwlrq1
Nlhihu +4<;3, sursrvhg d zlwklq0JOV hvwlpdwru zlwk duelwudu| lqwhuwhpsrudo fryduldqfh/
zkhuhdv Duhoodqr +4<;:, vxjjhvwhg d vlpsoh phwkrg iru rewdlqlqj urexvw hvwlpdwhv ri wkh
vwdqgdug huuruv wkdw doorz d jhqhudo fryduldqfh pdwul{1 Lq d g|qdplf sdqho prgho zlwk
vpdoo wlph glphqvlrq/ W / dqg odujh furvv0vhfwlrqdo glphqvlrq/ q/ Duhoodqr dqg Erqg +4<<4/
s1 5:<, sursrvhg d khwhurvnhgdvflw| frqvlvwhqw fryduldqfh pdwul{ zklfk lv urexvw wr jhqhudo
khwhurvnhgdvwlflw| ryhu lqglylgxdov dqg ryhu wlph exw lv qrw urexvw wr vhuldo fruuhodwlrq1 Vxfk
hvwlpdwruv zloo qrw eh ydolg zkhq wkhuh h{lvwv vhuldo fruuhodwlrq ri xqnqrzq irup1 Nh}gl
+5334, h{dplqhg wkh zlwklq hvwlpdwru zlwk vkruw wlph vhulhv1 Nh}gl vkrzhg vhuldo fruuhodwlrq
lq wkh huuru whupv dqg uhjuhvvruv zloo lqgxfh vhyhuh eldv lq wkh frqyhqwlrqdo vwdqgdug huuru
hvwlpdwhv lq sdqho gdwd prghov1
Uhfhqwo|/ KDF hvwlpdwruv kdyh ehhq xvhg lq qrqvwdwlrqdu| sdqhov/ h1j1/ Ndr +4<<<,/ Ndr
dqg Fkldqj +5333,/ dqg Skloolsv dqg Prrq +4<<<,1 Wkhvh dxwkruv xvh wkh nhuqho hvwlpdwruv
ghyhorshg iru wlph vhulhv prghov1 Riwhq/ d gdwd0gulyhq edqgzlgwk lv ghwhuplqhg dv d ixqfwlrq
ri W rqo|1 Dv zloo eh vhhq ehorz/ vxfk d surfhgxuh/ dowkrxjk rswlpdo iru wlph vhulhv prghov/ lv
qrw rswlpdo lq wkh sdqho frqwh{w1 Lq sduwlfxodu/ lw ryhuvprrwkhv wkh KDF hvwlpdwru ehfdxvh
lw grhv qrw wdnh lqwr dffrxqw wkh dgglwlrqdo vprrwklqj surylghg e| q1 Wklv lv dq xqghvludeoh
ihdwxuh ehfdxvh lw lv zhoo0nqrzq wkdw nhuqhov riwhq whqg wr xqghuhvwlpdwh wkh fryduldqfh
pdwul{hv dqg xqghuvprrwklqj zloo ohdg wr ixuwkhu grzqzdug eldv1 Rxu surfhgxuh zloo wdnh
wklv lqwr dffrxqw dqg wkh uhvxowv duh rswlpdo iru sdqho prghov1
Lq idfw/ KDF hvwlpdwruv duh htxdoo| lpsruwdqw lq sdqho prghov dv lq wlph vhulhv prghov1
Iru h{dpsoh/ lq vwdwlf sdqho prghov/ wkh zlwklq hvwlpdwru lv vwloo frqvlvwhqw zkhq wkhuh
h{lvwv vhuldo fruuhodwlrq ri xqnqrzq irup/ exw wkh vwdqgdug fryduldqfh pdwul{ hvwlpdwruv
wkdw dvvxph qr vhuldo fruuhodwlrq zloo eh lqydolg1 Lq wklv fdvh/ wkh xvh ri frqyhqwlrqdo w0whvwv
dqg I 0whvwv zloo ohdg wr plvohdglqj frqfoxvlrqv/ h1j1/ Ekdujdyd hw do1 +4<;5/ s1878,1
Hvwlpdwlrq ri KDF fryduldqfh pdwulfhv lv d orqj0vwdqglqj sureohp lq wlph vhulhv hfrqr0
phwulfv/ h1j1/ Qhzh| dqg Zhvw +4<;:/ 4<<7,/ Dqguhzv +4<<4,/ Dqguhzv dqg Prqdkdq +4<<5,/
ghq Kdqq dqg Ohylq +4<<;,/ dqg Krqj dqg Ohh +5333,1 Ohdglqj h{dpsohv lq sdqho frqwh{wv
wkdw pd| uhtxluh xvlqj KDF hvwlpdwruv duh hvwlpdwlrq ri dv|pswrwlf fryduldqfh pdwulfhv ri
ohdvw vtxduh hvwlpdwruv lq olqhdu/ qrqolqhdu dqg xqlw urrw2frlqwhjudwlrq uhjuhvvlrq prghov/ ri
wzr0vwdjh ohdvw vtxduhv/ wkuhh0vwdjh ohdvw vtxduhv/ txdvl0pd{lpxp olnholkrrg dqg jhqhudol}hg
phwkrg ri prphqw +JPP, hvwlpdwruv1 Vxfk fryduldqfh pdwul{ hvwlpdwlrq lv lpsruwdqw iru
frqghqfh lqwhuydo hvwlpdwlrq/ lqihuhqfh dqg k|srwkhvlv whvwlqj lq g|qdplf frqwh{wv1 Wr