# Tri-Join (Obj)

### Description
Matches all inputs on their first column and outputs the second column of each.

### Input
- `A [OBJ,OBJ]`: a list of pairs to be matched on its first column
- `B [OBJ,OBJ]`: a list of pairs to be matched on its first column
- `C [OBJ,OBJ]`: a list of pairs to be matched on its first column

### Output
- `A2B2C2 [OBJ,OBJ,OBJ]`: All the columns not involved in the match


Output scores can be [aggregated](docs://score_aggregation) and/or [normalised](docs://score_normalisation).