Toward Machine Learning with the Unit as a Primitive: Learning from Unit-Linked Events
Abstract
Machine learning is usually formalized through samples, while the persistent individual to which multiple observed or possible events refer often remains implicit. We propose the unit as an explicit primitive at the level of task semantics. A learning task first declares a population of persistent referents and a sameness criterion; the realized value denotes the selected referent. Supervised learning is the main formal specialization. Its semantic object is a family of unit-conditioned response laws. Homogeneity is the special case in which those laws coincide; a sample-only conditional is silent as to whether the world is homogeneous or the observed law is only the marginal of a heterogeneous family. What is learned from data is a pair : a tokenizer that produces a contextual unit token and one shared response-law form that reads it. The structured class takes that form to be a simple relation in the token; a linear predictor is the running instance. The token is the learner-side representation through which the task-side unit affects prediction, while a learner specification that omits unit information is unit-insensitive; homogeneity remains a property of the world-side response family. When identity is unresolved, the world-side law mixes unit-conditioned targets, while the learner composes its shared form with a token. A trusted resolver may fix the unit and supply a lookup token; otherwise unit abduction forms a token of the same type from factual evidence. Unlinked single-row observations can fail to distinguish a heterogeneous unit world from a homogeneous pooled world; trusted same-unit pairs separate a restricted witness. The formal results concern this supervised specialization.
Figures & tables
| Access to | unit-homogeneous response | unit-heterogeneous response |
|---|---|---|
| resolved or informative | The referent may be resolved directly, or the formed token may be informative; this response target is invariant across units. | Personalization is substantive; a resolved identity or an informative token changes the prediction. |
| unresolved; uninformative | Unit uncertainty remains at the population level; the response is unit-invariant. | Oracle predictive value of knowing may exist, but the current evidence cannot access it; mix, abstain, or collect new evidence. |
| Object in the unit formulation | Recommendation interpretation |
|---|---|
| Population | |
| population unit | possible user individuals |
| Individual referent | |
| realized unit | one persistent user; not a uniquely identified embedding coordinate |
| Direct-access model | |
| trusted key | stable referential address that associates interaction records and parameter updates with the same user slot |
| Family | Established object or assumption | Relation to the unit formulation |
|---|---|---|
| random effects | A supplied subject or group index and a population model for subject-specific parameters [ 25 , 13 ] . | Direct lookup of a subject token with a shared ; the random effect is a distributional token, not a private response mechanism. |
| latent-variable models and mixtures of experts | Incomplete-data estimation, input-dependent gating over experts, and amortized inference over latent codes [ 9 , 20 , 23 ] . | The encoder or gating map is a tokenizer; the decoder or expert family is a shared form, provided the task assigns the latent the role of a persistent unit. |
| multitask, grouped-latent, Neural-Process, and meta-learning methods | Shared parameters or representations across related tasks, and dataset-, group-, or task-level latents or deterministic context representations derived from an already associated context set [ 6 , 1 , 10 , 5 , 12 , 11 , 16 ] . | An episode or context encoder is a tokenizer and the decoder is a shared form, provided the outer task declares a persistent unit. In the cited methods the context-to-group association is supplied before prediction, which differs from forming a token from otherwise unattributed evidence. |
| record linkage, entity resolution, and probabilistic identity representations | Posterior linkage structures, learned entity matching, and distribution-valued instance representations [ 41 , 42 , 22 , 26 , 30 , 39 ] . | These methods infer which records share a task-side unit. The present formulation additionally asks for a learner-side token that instantiates one shared . |
| recommenders and personalization | Known user indices, latent user factors, history encoders, and user-conditioned response scores [ 28 , 24 , 37 , 18 , 21 , 27 ] . | A known user index provides a lookup token while the scoring model is a shared . Unresolved user attribution forms a token of the same type rather than looking it up. |
| potential outcomes, structural causal models, and Abductive Learning | units under treatment comparisons, counterfactual abduction–intervention–prediction, and logical abduction coupled to learning [ 35 , 32 , 31 , 8 ] . | Here remains a task-side referent across treatments or worlds. Their abduction objects (noise, logical facts, identity posteriors) are not the unit token of assumption 1 , and each tradition keeps its own estimands and identification conditions. |
Appendix figures & tables3 assets
Supplementary material from the paper’s appendix.
Appendix
| Symbol | Intended type | Boundary |
|---|---|---|
| World and population | ||
| population unit selection variable | which individual in | |
| population unit law | which-individual randomness under | |
| Fixed individual and event | ||
| realized persistent unit | fixed value of ; indexes a unit-conditioned law but is not synonymous with a learned numerical representation | |
| fixed-individual law | retains exogenous/event variation after | |
| Case or class | Restriction | Meaning |
|---|---|---|
| sample-only | no persistent unit is declared | Learns a row-level law such as ; it makes no direct statement about persistent individuals. |
| homogeneous unit extension | for -almost every | After persistent units are declared, unit identity adds no response information at the queries in . |
| pure-unit, input-invariant | while varies with | Outcomes vary across units while remaining invariant to the supplied query. |
| structured unit-responsive class | ; simple relation in a token, linear running instance ( Definition 2 ) | Both query and unit may matter. The running instance is a linear predictor in the unit token ; other declared simple maps of instantiate the same class. may be nonlinear in the query . |
| saturated unit-responsive class | is otherwise unrestricted across units | The class permits one arbitrary response family per unit, including homogeneous families; unseen-unit learning requires additional structure or information. |
| Unit formalism | DiscoSCM object | Additional causal content |
|---|---|---|
| population law | unit selection variable with law | Population over individuals participating in a structural causal system. |
| realized unit | individual retained across factual and counterfactual worlds | The same referent appears in every structural assignment . |
| fixed-unit event variation | exogenous variables | A realized event depends on both ; fixing need not make the outcome deterministic. |
| response law | law induced by | The response is generated by a directed mechanism rather than specified only as a conditional kernel. |
| response query | intervention value in | Reading a query as an intervention requires the causal graph, structural assignments, and an intervention semantics. |
| factual evidence | an observed factual trace | Evidence updates unit information about the already-realized unit; DiscoSCM represents that update as an identity posterior, which is one specialization of a formed token. The trace may also contain variables with separately declared direct response roles. |