# Compound Term Transparency Correction (G16 Update)

**Date:** 2026-04-23 01:18
**Status:** Empirically validated in MeTTa runtime
**Corrects:** G16 finding (2026-04-09) that claimed compound terms were opaque wholes

## Finding
All compound term operators are TRANSPARENT to NAL |- inference across ALL inference types.

## Operators Tested
| Operator | Example | Result |
|----------|---------|--------|
| & (intersection) | penguin->(& bird mammal)->vertebrate | stv 0.5 0.405 |
| \| (union) | penguin->(\| bird mammal)->vertebrate | stv 0.8 0.648 |
| Nested | eagle->(& (\| bird mammal) flying)->airborne | stv 0.855 0.69 |
| Difference | dog->(Difference animal fish)->land-dweller | stv 0.765 0.62 |

## Inference Types
Compound terms work identically in deduction, abduction, and induction.

## Note
Use `Difference` not `-` for set difference (minus sign causes parse errors).
## Sequential Compounds (seq)
- `(seq A B)` is transparent to deduction: stv 0.72 0.5832
- Order preserved: (seq A B) != (seq B A) structurally (non-commutative)
- **Limitation:** seq compounds do NOT auto-decompose for multi-step chaining
- morning-routine inside (seq X morning-routine) is not matched to standalone morning-routine
- Temporal chaining requires explicit bridge premises or flattening

## Product Compounds (×)
- `(× wings feathers)` is transparent to deduction: robin→bird→(× wings feathers) stv 0.765 0.62
- Product operator works identically to other compounds
- Complete operator map: &, |, Difference, seq, × — all transparent