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- competitive pools
- inhibitory and excitatory connections
- the output function of a unit in an IAC net

**Solution:**
An IAC network is a collection of nodes and weighted connections,
normally bidirectional connections.

The nodes are divided into competitive pools. All the interconnections between nodes in any pool are inhibitory; i.e. their weights are negative.

Connections between nodes in different pools, when they exist, are excitatory connections - i.e. the weights are positive. (Nodes are unconnected iff the weights are zero.)