PROTACs Sub-Experiment 1: Controlling Linker Length. Link-INVENT was tasked with generating linker ideas of variable length while keeping physico-chemical properties within a specified range (Fig. , see Supporting Information Fig. -16 for all training plots). The baseline experiment does not enforce a specific effective linker length interval and the distribution of lengths span a large range (Fig. ). In contrast, one can enforce the Link-INVENT agent to explore effective linker lengths within a certain interval, as shown by the enrichments observed in Fig. , e.g., the 'enforce 4-6' experiment enforced effective linker lengths in the interval [4-6] and the corresponding bar is enriched relative to other lengths. The purpose of this Sub-Experiment is to show the ease in which one can control effective linker length exploration, mimicking a real-world PROTAC linker design campaign. PROTACs Sub-Experiment 2: Controlling Linker Linearity. Link-INVENT was tasked with generating linker ideas with effective length in the interval [7,9] while keeping physico-chemical properties within a specified range and controlling linearity (Fig. , see Supporting Information We note that while the component itself is meant to be a descriptor of linker flexibility, inherent limitations exist, e.g., not accounting for intra-molecular hydrogen-bonding interactions which would rigidify the linker. Link-INVENT was tasked with generating linker ideas with variable ratios of rotatable bonds where we define 'Low', 'Moderate', and 'High' as the intervals [0,30], [40,60], and [70,100], respectively (Fig. , see Supporting Information Fig. for all training plots). Examples of linkers possessing variable degrees of flexibility are shown in Fig. . The agent implicitly learns that linkers containing rings and sp2 hybridized atoms are more rigid. A clear transition from "Low" flexibility to "High" flexibility is marked by increasing linearity and sp3 hybridized atoms. Without enforcing any length constraints, proposed linkers become increasingly longer to achieve a high "linker ratio of rotatable bonds" value. This is exemplified in the example linker in the "High" experiment (Fig. ).