On the semantics of em: polysemy, synonymy and competition in the prepositional system of Brazilian Portuguese

The preposition em is the most frequently used spatial item in Brazilian Portuguese (Ilari et al., 2015), a fact often attributed to its high degree of polysemy (Oliveira & GoodGod, 2018; Rodrigues et al. 2020). This paper aims to investigate the polysemy of em within the theoretical frameworks of Nanosyntax and Formal Semantics, with a focus on understanding how its different interpretations arise from the interaction between formal features of syntactic computation and encyclopedic knowledge. Methodologically, the analysis combines nanosyntactic decomposition of the universal functional sequence with semantic diagnostics, enabling us to identify which spatial properties are formally encoded and which emerge from conceptual factors. We propose that the notions of adjacency, contact, and inclusion, widely recognized in the descriptive literature, should be treated as independent features in the f-seq, built incrementally. Within this perspective, the core interpretations associated with em can be derived through the Superset Effect (Caha et al., 2025): inclusion presupposes contact, which in turn presupposes adjacency. The findings further indicate that finer interpretive nuances emerge from the encyclopedic component, especially from the interaction between Figure and Ground. Grounds denoting volumetric entities license all three readings (adjacency, contact, and inclusion), while Grounds denoting surface entities restrict interpretation to contact only. Finally, we discuss cases of competition between em and complex prepositional phrases such as dentro de, showing how the interplay between nanosyntactic structure and encyclopedic knowledge accounts for the distribution of relevant spatial readings in Brazilian Portuguese.