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AMPL, an acronym for "A Mathematical Programming Language," is a high-level language specifically designed for mathematical optimization. Introduced in the late 1980s by Robert Fourer, David Gay, and Brian Kernighan at Bell Laboratories, it has become a popular tool in operations research and analytics. AMPL allows users to describe optimization problems in a format similar to mathematical notation, making it easier to understand and modify models. It supports a wide range of optimization solvers and provides interfaces for data manipulation. The information about AMPL can be found on its official website and various scholarly articles about programming languages.

Ask the right questions secure the right AMPL talent among an increasingly shrinking pool of talent.

First 20 minutes

General AMPL app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in AMPL application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you define AMPL?

AMPL is a comprehensive and powerful algebraic modeling language for linear and nonlinear optimization problems, in discrete or continuous variables.

What are the main components of an AMPL model?

The main components of an AMPL model are: decision variables, objective function, and constraints.

Describe the difference between a parameter and a variable in AMPL.

In AMPL, a parameter is a value that is constant during the optimization process, while a variable is a value that the solver can change to satisfy the constraints and optimize the objective function.

How would you declare a variable in AMPL?

In AMPL, a variable can be declared using the 'var' keyword, followed by the name of the variable and optionally its type and bounds. For example: 'var x, >=0;' declares a non-negative variable named x.

What are the types of constraints in AMPL?

In AMPL, constraints can be equality constraints (using the '=' operator) or inequality constraints (using the '<=' or '>=' operators).

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What you’re looking for early on

Does the candidate have a strong understanding of AMPL programming language?

Is the candidate able to solve complex problems using AMPL?

Does the candidate have relevant experience in using AMPL for large-scale projects?

Is the candidate familiar with the latest updates and trends in AMPL?

Next 20 minutes

Specific AMPL development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

How would you define an objective function in AMPL?

An objective function in AMPL can be defined using the 'maximize' or 'minimize' keyword, followed by the name of the objective function and its mathematical expression. For example: 'minimize cost: 5*x + 3*y;'

What is the role of a solver in AMPL?

In AMPL, a solver is a software component that implements an optimization algorithm. The solver takes the model defined in AMPL, along with the data, and finds the values of the decision variables that optimize the objective function subject to the constraints.

What are the steps to solve an optimization problem in AMPL?

The steps to solve an optimization problem in AMPL are: define the model, load the data, choose a solver, solve the problem, and display the results.

How would you handle data in AMPL?

Data in AMPL can be handled in several ways. It can be defined directly in the model file, it can be loaded from a separate data file, or it can be read from a database.

What is the use of the 'set' keyword in AMPL?

In AMPL, the 'set' keyword is used to declare a set. A set is a collection of unique elements, and it can be used to index parameters, variables, and constraints.

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At this point, a skilled AMPL engineer should demonstrate strong problem-solving abilities, proficiency in AMPL programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with AMPL.

What does this simple AMPL code do?
param n;
var x{1..n} >= 0;
maximize obj: sum{i in 1..n} x[i];
solve;
This code defines a simple linear programming problem in AMPL. It declares a parameter 'n', a non-negative variable 'x' with 'n' elements, and an objective function to maximize the sum of all elements in 'x'. The 'solve' statement then solves the problem.
What is the output of this AMPL code?
set A := 1, 2, 3;
set B := 2, 3, 4;
print A union B;
The output will be the union of sets A and B, which is the set {1, 2, 3, 4}.
What does this AMPL code do?
param n;
set S := 1..n;
param a {S} default 0;
let a[1] := 1;
let a[2] := 2;
print a;
This code declares a set 'S' with 'n' elements, and an array 'a' indexed over 'S' with default value 0. Then it sets the first two elements of 'a' to 1 and 2 respectively, and prints the array 'a'.
What does this AMPL code do?
param n;
var x {1..n} integer >= 0, <= 1;
subject to Constraint{i in 1..n}: sum{j in 1..n} x[j] >= i;
solve;
This code defines a binary integer programming problem in AMPL. It declares a binary variable 'x' with 'n' elements, and a set of constraints that the sum of all elements in 'x' is greater than or equal to each index 'i'. The 'solve' statement then solves the problem.

Wrap-up questions

Final candidate for AMPL Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle AMPL application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

How would you model a nonlinear objective function in AMPL?

A nonlinear objective function in AMPL can be modeled using the same 'maximize' or 'minimize' keyword as a linear objective function, but the mathematical expression can include nonlinear terms. For example: 'minimize cost: x^2 + y^2;'

What is the difference between a 'within' and a 'in' statement in AMPL?

In AMPL, the 'within' keyword is used to specify the domain of a variable or parameter, while the 'in' keyword is used to specify the elements of a set.

How would you model a binary variable in AMPL?

A binary variable in AMPL can be modeled by declaring a variable with the 'binary' keyword. For example: 'var x binary;' declares a binary variable named x.

AMPL application related

Product Perfect's AMPL development capabilities

Beyond hiring for your AMPL engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in AMPL projects, and can engage in multiple capacities.

AMPL Consultive assessments

AMPL Application Conversion Assessment AMPL Application Integration Assessment AMPL Data & Database Integration Assessment

Custom AMPL development projects

Custom AMPL App Conversion AMPL Custom App Development Process App UI Design for AMPL Facelifts

Hiring guide for AMPL Engineers

AMPL Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

What you’re looking to see on the AMPL engineer at this point.

AMPL Consultive assessments

Custom AMPL development projects