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From Verification to Synthesis Sumit Gulwani Microsoft Research, Redmond August 2013 Marktoberdorf Summer School Lectures: Part 1.

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Presentation on theme: "From Verification to Synthesis Sumit Gulwani Microsoft Research, Redmond August 2013 Marktoberdorf Summer School Lectures: Part 1."— Presentation transcript:

1 From Verification to Synthesis Sumit Gulwani sumitg@microsoft.com Microsoft Research, Redmond August 2013 Marktoberdorf Summer School Lectures: Part 1

2 1 Synthesis Goal: Synthesize a computational concept in some underlying language from user intent using some search technique. State of the art: We can synthesize programs of size 10-20.

3 Language –Programs Straight-line programs –Automata –Queries User Intent –Logic, Natural Language –Examples, Demonstrations/Traces –Program Search Technique –SAT/SMT solvers (Formal Methods) –A*-style goal-directed search (AI) –Version space algebras (Machine Learning) 2 Dimensions in Synthesis PPDP 2010: “Dimensions in Program Synthesis”, Gulwani. (Application) (Ambiguity) (Algorithm)

4 3 Compilers vs. Synthesizers DimensionCompilersSynthesizers Concept Language Executable ProgramVariety of concepts: Program, Automata, Query, Sequence User IntentStructured languageVariety/mixed form of constraints: logic, examples, traces Search Technique Syntax-directed translation (No new algorithmic insights) Uses some kind of search (Discovers new algorithmic insights)

5 From verification to synthesis –Bitvector algorithms (PLDI 2011, ICSE 2012) –General loopy programs (POPL 2010) –SIMD algorithms (PPoPP 2013) –Program inverses (PLDI 2011) –Graph algorithms (OOPSLA 2010) End-user Programming (Examples & Natural Language) –Syntactic string transformations: Flash Fill (POPL 2011) –Semantic string transformations (VLDB 2012) –Table layout transformations (PLDI 2011) –Smartphone scripts (MobiSys 2013) Computer-aided Education –Problem Synthesis (AAAI 2012, CHI 2013) –Solution Synthesis (PLDI 2011, IJCAI 2013) –Feedback Synthesis (PLDI 2013, IJCAI 2013) –Content Authoring (CHI 2012) 4

6 ApplicationGenerating Synthesis Constraint Solving Synthesis Constraint BitvectorLocation variablesCEGIS + SMT Loopy Alg.Template-basedSMT SIMDRelational verificationCEGIS + Reachability value graph InversesTemplate-based + symbolic execution SMT Graph Alg. From Verification to Synthesis 5 Reference: Path-based Inductive Synthesis for Program Inversion, PLDI 2011, Srivastava, Gulwani, Chaudhuri, Foster

7 Language –Programs Straight-line programs –Automata –Queries User Intent –Logic, Natural Language –Examples, Demonstrations/Traces –Program Search Technique –SAT/SMT solvers (Formal Methods) –A*-style goal-directed search (AI) –Version space algebras (Machine Learning) 6 Dimensions in Synthesis

8 In-place run-length encoding: A = [1,1,1,0,0,2,2,2,2] Encoder A=[1,0,2] N=[3,2,4] Decoder A’=[1,1,1,0,0,2,2,2,2] Program Inversion: Example 7 IN(A,n); Assume (n >= 0) i, m := 0, 0; // parallel assignment while (i<n) r := 1; while (i+1<n && A[i]=A[i+1]) r, i := r+1, i+1; A[m], N[m], m, i := A[i], r, m+1, i+1; OUT(A,N,m); IN(A,N,m) i’, m’ := 0, 0; while (m’ < m) r’ := N[m’]; while (r’>0) r’,i’, A’[i’] := r’-1, i’+1, A[m’]; m’ := m’+1; OUT(A’,m’); assert(A’=A; m’=n);

9 In-place run-length encoding: A = [1,1,1,0,0,2,2,2,2] Encoder A=[1,0,2] N=[3,2,4] Decoder A’=[1,1,1,0,0,2,2,2,2] Program Inversion as Synthesis Problem 8 IN(A,n); Assume (n >= 0) i, m := 0, 0; // parallel assignment while (i<n) r := 1; while (i+1<n && A[i]=A[i+1]) r, i := r+1, i+1; A[m], N[m], m, i := A[i], r, m+1, i+1; OUT(A,N,m);

10 Synthesis Technique 9

11 Reference: Program Synthesis by Sketching, Phd Thesis 2008, Armando Solar-Lezama (Advisor: Ras Bodik @ UC-Berkeley) Key Ideas: –Write an arbitrary program with holes, where each hole takes values from a finite domain. –Use CEGIS to generate SAT constraints on holes. Cons: Not as efficient as domain-specific synthesizers. –(On bitvector benchmark, times out on 9/25 tasks, and on the remaining it is slower by 20x on average). Pros: –A very powerful formalism that can be used to model a variety of synthesis problems. –Sees synthesis as an interactive process. Related Work: Program Sketching 10


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