AMPL+ Developer Hiring Guide

Hiring Guide for AMPL+ Engineers

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

AMPL+ is a high-level programming language specifically designed for mathematical optimization. Developed in the late 1980s by Robert Fourer, David Gay, and Brian Kernighan at Bell Laboratories, it offers an algebraic modeling language that simplifies the creation and maintenance of large-scale optimization problems. AMPL+'s unique design allows for seamless integration with various solvers and data sources. It is considered a powerful tool in operations research and analytics, widely used in industries ranging from logistics to energy planning. Sources of information on AMPL+ include academic publications, official documentation, and the creators' book "AMPL: A Modeling Language for Mathematical Programming".

First 20 minutes

General AMPL+ knowledge and experience

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

How would you define a constraint in AMPL+?

You can define a constraint in AMPL+ by using the 'subject to' keyword followed by the constraint name and its mathematical expression.

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

In AMPL+, a parameter is a constant value that does not change during the optimization process, while a variable is a value that the solver can change to optimize the objective function.

What is the purpose of the 'set' element in AMPL+?

The 'set' element in AMPL+ is used to define a collection of items, which can be used in parameters, variables, constraints, and objectives.

How would you define a variable in AMPL+?

You can define a variable in AMPL+ by using the 'var' keyword followed by the variable name and optionally its bounds.

What are the basic elements of an AMPL+ model?

The basic elements of an AMPL+ model are parameters, variables, objectives, and constraints.

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What youre looking for early-on

Has the candidate demonstrated a good understanding of algorithms and data structures?

These are fundamental concepts in programming and are essential for writing efficient and effective code in AMPL+.

Does the candidate show a willingness to learn and adapt?

The tech industry is constantly evolving, so it's important for developers to be open to learning new skills and adapting to changes.

Does the candidate have relevant experience or projects?

Previous experience or projects in AMPL+ will show that the candidate can apply their skills in a practical setting.

Is the candidate able to communicate effectively?

Communication skills are important for understanding project requirements, working within a team, and explaining technical information to non-technical colleagues.

Has the candidate demonstrated problem-solving skills?

Problem-solving is a key skill for developers as they will often need to find solutions to complex coding issues.

Does the candidate have a strong understanding of AMPL+?

This is crucial as the job position is for an AMPL+ developer. They should be able to demonstrate their knowledge and experience with this programming language.

Next 20 minutes

Specific AMPL+ development questions

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

How would you write a multi-objective optimization problem in AMPL+?

AMPL+ does not directly support multi-objective optimization. However, you can write a multi-objective optimization problem by transforming it into a single-objective problem using techniques such as weighted sum method or goal programming.

Describe the difference between 'in' and 'within' keyword in AMPL+.

'In' keyword is used to specify a set that a parameter or variable belongs to, while 'within' keyword is used to specify the bounds of a variable.

How would you specify a data file in AMPL+?

You can specify a data file in AMPL+ by using the 'data' keyword followed by the file name.

What are the two types of objective functions in AMPL+?

The two types of objective functions in AMPL+ are 'minimize' and 'maximize'.

What is the role of the 'solve' statement in AMPL+?

The 'solve' statement in AMPL+ is used to start the optimization process. It instructs the solver to find the optimal values of the variables that minimize or maximize the objective function subject to the constraints.

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The ideal back-end app developer

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

At this point, a skilled AMPL+ engineer should have demonstrated strong problem-solving skills, a deep understanding of AMPL+ language and its applications, and excellent communication skills. Red flags would include a lack of specific experience or knowledge about AMPL+, inability to explain complex concepts, or poor problem-solving abilities.

Digging deeper

Code questions

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

What does the following AMPL+ code do?

var x >= 0, <= 10, integer;

This code declares an integer variable 'x' with a lower bound of 0 and an upper bound of 10.

What will be the output of the following AMPL+ code?

param n := 5; set S := 1..n; display S;

The output will be a set S containing the numbers from 1 to 5.

What does the following AMPL+ code do?

param n := 5; set S := 1..n; set T := {i in S | i mod 2 = 0};

This code creates a set T that contains all even numbers from the set S.

What does the following AMPL+ code do?

param n := 5; set S := 1..n; minimize cost: sum {i in S} i;

This code defines an optimization problem that minimizes the sum of the numbers in set S.

What does the following AMPL+ code do?

param n := 5; set S := 1..n; var x{i in S} >= 0, <= 10, integer;

This code declares a set of integer variables 'x' indexed by set S with a lower bound of 0 and an upper bound of 10.

What will be the output of the following AMPL+ code?

param n := 5; set S := 1..n; var x{i in S} >= 0, <= 10, integer; minimize cost: sum {i in S} i*x[i]; solve;

This code solves an optimization problem that minimizes the sum of the products of the numbers in set S and their corresponding variables 'x'. The output will be the optimal solution to this problem.

Wrap-up questions

Final candidate for AMPL+ role questions

The final few interview questions for a AMPL+ candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.

What are the limitations of AMPL+?

Some limitations of AMPL+ include lack of support for multi-objective optimization and uncertainty in parameters, difficulty in handling complex non-linear models, and requirement for a separate solver to solve the model.

How would you implement a piecewise linear function in AMPL+?

You can implement a piecewise linear function in AMPL+ by using the 'PL' keyword followed by the points that define the function.

Describe the difference between 'let' and 'param' keyword in AMPL+.

'Let' keyword is used to assign a value to a parameter or variable in the model, while 'param' keyword is used to define a parameter.

How would you handle uncertainty in parameters in AMPL+?

AMPL+ does not directly support uncertainty in parameters. However, you can handle uncertainty by using techniques such as stochastic programming or robust optimization, which involve defining scenarios or uncertainty sets for the parameters and modifying the model accordingly.

What is the purpose of the 'option' statement in AMPL+?

The 'option' statement in AMPL+ is used to set options for the solver, such as the solver name, time limit, and tolerance.

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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.