Irrelevance and Ambiguity

How can (oracle) knowledge of the trigger status of an input sentence affect learning?

The learner is inspecting a sentence S. Given the oracle knowledge, they know that this sentence either

• contains a global trigger for Pi=0 or 1.
• is known to be ambiguous evidence wrt Pi. Some languages with Pi=0 license it, as do some with Pi=1.
• is irrelevant as evidence wrt Pi.

They use this knowledge to inform how they incorporate S into their hypothesis-updating procedure.

A note on parameter numbering

(because I keep mixing this up.)

The parameters are listed and numbered from left to right. SP, HIP, HCP etc are parameter numbers 1, 2, 3 etc. In the integer grammar id representation of a grammar, these are the three most significant bits.

Subject position (SP) is parameter #1, which corresponds to the 13th bit in the integer grammar id and binary bitstring.

• 0000000000000 has SP=0 (subject initial)
• 1000000000000 (grammar id 4096) has parameter 1, SP, set to 1 (subject final).

Q-inversion (QInv) is parameter #13, which corresponds to the 1st bit in the grammar bitstring.

• 0000000000000 has QInv off (no question inversion)
• 0000000000001 (grammar id 1) has Qinv, parameter 13, set to 1 (obligatory question inversion).