Chapter 15 - People

More documents

Recommendations

Info

372 NEOMYCIN: Reconfiguring an Expert System for Application to Teachingobserved STOP-EXPLORING METARULE407Repeating EHS loop: focus = INFECTIOUS-PROCESStask METARULE427 succeeded.The first step is again to review the differential, a process observed in experts. Process features of brainabscess and chronic meningitis are compared: they both occur in the central nervous system, are chronicproblems, and are infectious, but brain abscess is a localized problem. NEOMYCIN asks a question todiscriminate on this basis . ...Review differential: BRAIN-ABSCESS HEMATOMAPUS-IN-BRAIN CHRONIC-MENINGITISEnter G&D loop: focus = INFECTIOUS-PROCESStask METARULE397 succeeded.6) Does Mike have focal neurological signs?•• NOTrying evidence rules: FOCALSIGNS ---+ BRAIN-ABSCESSRULE179 failed due to clause 1The program has not been supplied with knowledge for confirming other causes of mass lesion (e.g.,traumatic hemorrhage, tumor), so it is unable to continue its grouping operation and begins an explorationcycle ....Repeating G&D loop: focus = INFECTIOUS-PROCESSRepeating EHS loop: focus = INFECTIOUS-PROCESStask METARULE428 succeeded.Enter E&R loop: focus = INFECTIOUS-PROCESStask METARULE402 succeeded.Enter PH loop: focus = BRAIN-ABSCESStask METARULE409 succeeded.Now directly focusing on brain abscess, the program "realizes" that data supplied earlier are relevant(RULE433). Chronic meningitis is then considered by refining it and pursuing specific causes. Pursuing TB,NEOMYCIN follows the strategy of confirming the first ("enabling") step in the disease process: contCict withthe organism ....Trying evidence rules: MASS-LESION ---+ BRAIN-ABSCESSTrying RULE433; succeeded.Conclude: INFECTIOUS-PROCESS is BRAIN-ABSCESS (.216)Observed STOP-PURSUING METARULE408Repeating E&R loop: focus = BRAIN-ABSCESStask METARULE429 succeeded.Enter PH loop: focus = TB-MENINGITIStask METARULE411 succeeded.7) Does Mike have a TB risk factor?•• YESTrying evidence rules: TBRISK ---+ TB-MENINGITISTrying RULE525; succeeded.observed STOP-PURSUING METARULE408Focusing strategies dictate that a sibling be considered next. Fungal meningitis is refined, and a child,cryptococcus, pursued . ...Repeating E&R loop: focus = TB-MENINGITIStask METARULE401 succeeded.Enter PH loop: focus = FUNGAL-MENINGITISFIGURE <strong>15</strong>-4 continued
A Sample Case 373Repeating E&R loop: focus = FUNGAL-MENINGITIStask METARULE399 succeeded.Enter PH loop: focus = CRYPTOCOCCUSA cancer patient is at some risk of getting cryptococcal meningitis. Rather than asking directly if the patienthas cancer, the program models an expert's efficient casting of a wider net by asking a more generalquestion. Specifically, there are "screening rules," that lead it to determine first if the patient isimmunosuppressed (RULE39S) and then compromised (RULE343). This is the only form of backwardchaining that occurs in NEOMYCIN. 2task METARULE431 succeeded.--[0] Findout: LEUKEMIA--[1] Findout: IMMUNOSUPPRESSEDTrying RULE343;8) Is Mike a compromised host (e.g. alcoholic, sickle-cell-disease,immunosuppressed)?** YESRULE343 failed due to clause 1If the patient were not compromised, the program could have concluded that he is not immunosuppressed(RULE343). Now it is unsure and must ask direct/yo If the patient is not immunosuppressed, the program willknow that he does not have leukemia (RULE39S). The answer of LEUKEMIA below impliesimmunosuppressed, so RULE39S fails, and the original goal is determined.--[1] Finished: IMMUNOSUPPRESSED9) Is Mike immunosuppressed (e.g. corticosteroid therapy, cytotoxic drugtherapy, radiation therapy, leukemia)?** LEUKEMIAI will assume that leukemia is one of the diagnoses of MikeRULE395 failed due to clause 1--[0] Finished: LEUKEMIATrying evidence rules: LEUKEMIA -+ CRYPTOCOCCUSTrying RULE056; succeeded.Conclude: FUNGAL-MENINGITIS is CRYPTOCOCCUS (.3)Repeating E&R loop: focus = CRYPTOCOCCUStask METARULE401 succeeded.Attention turns to a sibling. Again, the "enabling step" is asked about first . ...Enter PH loop: focus = COCCIDIOIDEStask METARULE411 succeeded.10) Has the patient ever been to a cocci-endemic area?** NOTrying evidence rules: COCCI-ENDEMIC -+ COCCIDIOIDESRULE570 failed due to clause 1RULE287 failed due to clause 1observed STOP-PURSUING METARULE408Repeating E&R loop: focus = COCCIDIOIDESRepeating EHS loop: focus = COCCIDIOIDEStask METARULE430 succeeded.2Ed. notf: A later version of NEOMYCIN accomplishes this form of inference by meta-rules.
Page 1 and 2: 15NEOMYCIN:. Reconfiguring a Rule-B
Page 3 and 4: Introduction 363• representations
Page 5 and 6: Introduction 365IF: 1) The infectio
Page 7 and 8: An Overview of NEOMYCIN 367trigger
Page 9 and 10: A Sample Case 369METARULE397 (for t
Page 11: A Sample Case 371Differential:repla
Page 15 and 16: The Diagnostic Meta-Strategy 375Mak
Page 17 and 18: Etiological Taxonomy, Causal and Di
Page 19 and 20: Some Limitations 37915 • 6Related
Page 21: Future Research 381system. This is

Chapter 15 - People

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?