{"id":2409,"date":"2018-06-30T18:03:00","date_gmt":"2018-06-30T17:03:00","guid":{"rendered":"https:\/\/www.prover.com\/?p=2409"},"modified":"2024-06-20T10:34:48","modified_gmt":"2024-06-20T09:34:48","slug":"hll-formal-language","status":"publish","type":"post","link":"https:\/\/www.prover.com\/verification-validation\/hll-formal-language\/","title":{"rendered":"HLL formal language celebrates 10 years"},"content":{"rendered":"

The formal language HLL (High Level Language)<\/a> has emerged in\u00a0recent years as a quite popular language for formal verification of\u00a0safety-critical systems, especially in the railway signaling domain.\u00a0This year marks the 10th anniversary of its conception.<\/p>\n

The history of HLL<\/h3>\n

The language has its roots in the proof engine technologies developed\u00a0by Prover in the 1980s (St\u00e5lmarck’s method), 1990s (temporal\u00a0induction) and early 2000s (higher level theories) and its development\u00a0was prompted by a need for trusted (or certifiable) formal\u00a0verification.<\/p>\n

HLL is a declarative language with a broad panel of types and\u00a0operators and is suitable for modelling discrete-time sequential\u00a0behaviors and expressing properties of these behaviors.<\/p>\n

Or to put it differently: if you have a reactive system (such as an\u00a0interlocking or a CBTC subsystem) with some inputs, outputs and\u00a0internal state (memory), and you want to formally prove that some\u00a0present or future conditions on the outputs shall follow from some\u00a0past or present conditions on the inputs, then HLL may be the right\u00a0language for you. The language, with its associated tools, can be used\u00a0for applications such as invariant checking, sequential equivalence\u00a0checking, test case generation or static code analysis (detection of\u00a0runtime errors such as overflows or divisions by zero).<\/p>\n

Version 1.0 of HLL was released in 2008 and the language is being\u00a0continually developed. The latest version includes, in addition to the\u00a0basic core of Boolean logic and integer arithmetic, features such as\u00a0enums, arrays, tuples, structs, recursive functions, quantifiers,\u00a0polymorphism, namespaces and blocks. The imperative dialect of HLL\u00a0also supports statements such as assignments, if-then-else, loops and\u00a0procedures.<\/p>\n

The HLL formal language success<\/h3>\n

The success of HLL can possibly be attributed to its ease of use\u00a0(flexible and intuitive) coupled with the support by formal\u00a0verification tools that both scale up in practice for a wide variety\u00a0of systems, and provide certifiable results based on diversification\u00a0and proof logging\/checking.<\/p>\n

Find out more about HLL here.<\/a>
\nYou can also check out our HLL Forum – The community for those who use HLL<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

The formal language HLL (High Level Language) has emerged in\u00a0recent years as a quite popular language for formal verification of\u00a0safety-critical […]<\/p>\n","protected":false},"author":19,"featured_media":14931,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"content-type":"","inline_featured_image":false,"footnotes":""},"categories":[154],"tags":[72],"class_list":["post-2409","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-verification-validation","tag-formal-methods"],"yoast_head":"\nHLL formal language celebrates 10 years - Prover - Engineering a Safer World<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.prover.com\/verification-validation\/hll-formal-language\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"HLL formal language celebrates 10 years - 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