Q6 — Rete Net: Property Classification
Lift/3BHK/MIG and lift/gym/3BHK joins on pno — three tuples make the conflict set and specificity hands it to R2's six tests.
The Question
A Rete net classifies properties. Working memory:
101. (Amenity ^pno 2E ^parking YES ^lift YES ^gym YES)
102. (Locality ^pno 2E ^class HIG ^mall YES ^bus-stop YES)
103. (Locality ^pno 1G ^class MIG ^bus-stop YES)
104. (Property ^pno 2E ^layout 3BHK ^floor 44)
105. (Property ^pno 1G ^layout 1BHK ^floor 1)
106. (Amenity ^pno 1G ^parking YES ^heating YES)
| # | Question | Official answer |
|---|---|---|
| 6.1 | Tuples in the conflict set (A: R1,103,105,106 · B: R2,101,102,104 · C: R3,101,103,106 · D: R4,103,105) | A, B, D |
| 6.2 | Specificity fires | B |
| 6.3 | Recency fires | A |
The Topic in 60 Seconds
Alpha nodes filter single WMEs (CLASS, then attribute tests); beta nodes join streams on the shared ^pno. Conflict set = all fully matched (rule, data…) tuples.
Deep-dive: The Rete Algorithm.
Step 1 — Locate every WME
Split WM by ^pno first — tuples never cross clusters:
| Cluster | WMEs | Contents |
|---|---|---|
| 2E | 101, 102, 104 | Amenity (parking/lift/gym) · Locality (HIG/mall/bus-stop) · Property (3BHK/floor 44) |
| 1G | 103, 105, 106 | Locality (MIG/bus-stop) · Property (1BHK/floor 1) · Amenity (parking/heating) |
Alpha-level notes: heating (WME 106) has no alpha node — the WME still sits in the parking leaf; floor 44 passes the floor > 10 test, floor 1 does not.
Step 2 — Test each option tuple at its beta joins
| Option | Tuple | Join check | Verdict |
|---|---|---|---|
| A | (R1, 103, 105, 106) | all ^pno = 1G: MIG (103) ⋈ 1BHK (105) ⋈ parking-amenity (106) ✓ | in |
| B | (R2, 101, 102, 104) | all ^pno = 2E: lift+gym (101) ⋈ 3BHK (104) ⋈ HIG+mall+bus-stop (102) ✓ | in |
| C | (R3, 101, 103, 106) | 101 lives at 2E but 103/106 at 1G — mixed cluster, no shared ^pno join | out |
| D | (R4, 103, 105) | all ^pno = 1G: MIG+bus-stop (103) ⋈ 1BHK (105) ✓ | in |
Conflict set = options A, B, D ✓
6.2 — Specificity → B
Count conditions (= WMEs bound in the tuple): R2's rule fires through six joined tests (lift, gym, 3BHK, HIG, mall, bus-stop); R1 carries three; R4 carries three. Most specific wins → B ✓
6.3 — Recency → A
Newest WME inside each surviving tuple:
| Tuple | Max timestamp |
|---|---|
| A (R1, 103, 105, 106) | 106 ← newest in WM |
| B (R2, 101, 102, 104) | 104 |
| D (R4, 103, 105) | 105 |
Highest timestamp wins → A ✓
Tricks & Tips
Answers: 6.1 A, B, D · 6.2 B · 6.3 A