Definition. Prompt serializer [ftip-006V]
Definition. Prompt serializer [ftip-006V]
Using the prompt space of Notation [ftip-002A], a prompt serializer is a declared map \[ s_{\mathrm {pr}}:\mathcal X_{\mathrm {pr}}\longrightarrow \mathcal V^*. \] For token strings \(u,v\in \mathcal V^*\), write \(u\mathbin {\Vert }v\) for their concatenation. A response token \(y_t\) is therefore predicted from the token prefix \(s_{\mathrm {pr}}(x)\mathbin {\Vert }y_{<t}\).
The serializer fixes system text, role markers, separators, and any other prompt-side control tokens. Changing it changes the conditional examples seen by the language model even when the abstract prompts and responses are unchanged.