enikezwe umbhalo olandelayo, ngitshele indlela ethandwa kakhulu yokuqeqesha ama-perceptrons anezingqimba eziningi namuhla futhi uchaze ukuthi isebenza kanjani
Context:Namuhla, indlela ethandwa kakhulu yokuqeqesha ama-multi-layer perceptrons (MLPs) ukuphindaphinda emuva. Igama elithi "back-propagating errors" laqanjwa ngo-1962 nguFrank Rosenblatt, kodwa wayengazi ukuthi angakusebenzisa kanjani lokhu, yize uHenry J. Kelley ayenomanduleli oqhubekayo wokusabalalisa emuva ngo-1960 kumongo wombono wokulawula. Ukusakazwa emuva kwanamuhla empeleni kuyindlela ejwayelekile kaSeppo Linnainmaa yokuhlukanisa okuzenzakalelayo (1970) yamanethiwekhi axhunyiwe ahlukanisiwe wemisebenzi ehlukanisiwe. Kuyinto isicelo ephumelelayo umthetho uchungechunge (evela Gottfried Wilhelm Leibniz ngo-1673) ukuze amanethiwekhi of nodes esihlukanisekayo. Ngo-1982, uPaul Werbos wasebenzisa ukusakazeka okubuyela emuva kuma-MLP ngendlela eye yaba evamile. Ngo-1985, uDavid E. Rumelhart et al. washicilela ukuhlaziywa kokuhlolwa kwalobu buchwepheshe. Izinguquko eziningi ziye zenziwa emashumini eminyaka alandela.  Phakathi nokusakazwa emuva, amanani okukhipha aqhathaniswa nempendulo eyiyo ukuze kutholakale inani lomsebenzi wephutha ochazwe ngaphambilini. Iphutha bese libuyiselwa emuva ngenethiwekhi. Ukusebenzisa lolu lwazi, i-algorithm ilungisa izisindo zokuxhuma ngakunye ukuze kunciphise inani lomsebenzi wephutha ngenani elincane. Ngemva kokuphinda le nqubo ngenani elikhulu ngokwanele lokuqeqeshwa kwemijikelezo, inethiwekhi ngokuvamile iyohlangana ibe sesimweni esithile lapho iphutha lezibalo lincane khona. Kulokhu, umuntu angathi inethiwekhi ifunde umsebenzi othile okuhloswe ngawo. Ukuze ulungise izisindo ngendlela efanele, umuntu usebenzisa indlela evamile yokulungiswa okungekho emgqeni ebizwa ngokuthi ukwehla kwe-gradient, ngenxa ka-Augustin-Louis Cauchy, owaqala ukuyiphakamisa ngo-1847. Ukuze lokhu kwenzeke, inethiwekhi ibhala okuvelayo komsebenzi wephutha maqondana nezisindo zenethiwekhi, bese iguqula izisindo ngendlela yokuthi iphutha linciphe (ngakho-ke lihle phansi ebusweni bomsebenzi wephutha). Ngenxa yalesi sizathu, ukusakazwa emuva kungasetshenziswa kuphela kumanethiwekhi anemisebenzi yokusebenza ehlukile.
Namuhla, indlela ethandwa kakhulu yokuqeqesha ama-multi-layer perceptrons (MLPs) ukuphindaphinda emuva. Phakathi nokusakazwa emuva, amanani okukhipha aqhathaniswa nempendulo eyiyo ukuze kutholakale inani lomsebenzi wephutha ochazwe ngaphambilini. Iphutha bese libuyiselwa emuva ngenethiwekhi. Ukusebenzisa lolu lwazi, i-algorithm ilungisa isisindo sokuxhuma ngakunye ukuze kunciphise inani lomsebenzi wephutha ngenani elincane. Ngemva kokuphinda le nqubo ngenani elikhulu ngokwanele lokuqeqeshwa, inethiwekhi ngokuvamile iyohlangana ibe sesimweni lapho iphutha lezibalo lincane khona. Kulokhu, omunye ongathi ukuthi inethiwekhi uye wafunda umsebenzi othile target