Leanstral 1.5 vs. Holo4

Leanstral 1.5 is a model under the Apache-2.0 license, crafted for proficient proof engineering within Lean 4, with the goal of improving both the functionality and accessibility of formal verification. This model features a remarkable total of 119 billion parameters, of which 6 billion are actively utilized, representing a major leap in efficiency for tasks related to theorem proving, agent-based proof engineering, and practical code verification. The evolution of Leanstral 1.5 included an extensive three-phase training regimen, which encompassed mid-training, supervised fine-tuning, and reinforcement learning through CISPO. In a multiturn environment, the model is designed to accept a theorem statement, propose a proof, and iteratively adjust its strategy based on input from the Lean compiler until the proof compiles successfully or resources run out. Operating in the code agent framework, Leanstral acts similarly to a developer navigating through a file system, enabling it to modify files, run bash commands, and engage with the Lean language server to track goals, errors, and type information in real time. This cutting-edge methodology not only simplifies the proof engineering workflow but also significantly enriches the overall user experience in formal verification tasks, making the process both more efficient and user-friendly. Furthermore, the integration of these capabilities positions Leanstral 1.5 as a transformative tool in the landscape of formal verification.

Holo4 is a family of agentic AI models developed by H Company for computer use and multi-step automation across desktop, web, mobile, terminal, MCP, and API environments. The series consists of Holo4 27B, a dense 27-billion-parameter model, and Holo4 35B-A3B, a 35-billion-parameter Mixture-of-Experts model with 3 billion active parameters. Rather than specializing exclusively in graphical interfaces or tool calling, Holo4 can click and type on screens, write and run its own code, and invoke MCP or API tools as different stages of a workflow require. The same model can therefore move between desktop applications, websites, Android applications, code sandboxes, and business APIs without switching to a separate model for each interface. H Company's Agentic Task Factory generated approximately 10,000 tasks across web applications, MCP servers, desktop software, and hybrid environments to support model development and evaluation. Holo4 underwent supervised fine-tuning on 127 billion tokens, with roughly three-quarters of that training data consisting of successful agentic trajectories covering desktop, web, MCP/API, and mobile tasks. Two reinforcement-learning experts were subsequently trained for desktop/web workflows and terminal/MCP/API workflows before being merged into the final generalist model. In H Company's evaluations, Holo4 27B scored 85.2% on OSWorld, 61.7% on OSWorld 2.0, 45.4% on AutomationBench, and 85.1% on AndroidWorld, although the company notes that reference-model results can use different harnesses and effort levels. Holo4 27B supports a 256K context window and is priced through the H Models API at $0.40 per million input tokens, $0.04 per million cached input tokens, and $3.00 per million output tokens. Holo4 35B-A3B also supports 256K context and is priced at $0.30 per million input tokens, $0.03 per million cached input tokens, and $2.00 per million output tokens.