readd file

src/blmo_interface.jl

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+"""
+    BLMO
+
+Supertype for the Bounded Linear Minimization Oracles
+"""
+abstract type BoundedLinearMinimizationOracle <: FrankWolfe.LinearMinimizationOracle end 
+
+###################################### Necessary to implement ####################################
+
+"""
+Implement `FrankWolfe.compute_extreme_point`
+
+Given a direction d solves the problem
+    min_x d^T x
+where x has to be an integer feasible point
+"""
+function compute_extreme_point end
+
+"""
+Read global bounds from the problem.
+"""
+function build_global_bounds end
+
+"""
+Add explicit bounds for binary variables, if not already done from the get-go.
+"""
+function explicit_bounds_binary_var end
+
+
+## Read information from problem
+
+"""
+Get list of variables indices. 
+If the problem has n variables, they are expected to contiguous and ordered from 1 to n.
+"""
+function get_list_of_variables end
+
+"""
+Get list of binary variables.
+"""
+function get_binary_variables end
+
+"""
+Get list of integer variables.
+"""
+function get_integer_variables end 
+
+"""
+Get the index of the integer variable the bound is working on.
+"""
+function get_int_var end
+
+"""
+Get the list of lower bounds.
+"""
+function get_lower_bound_list end
+
+"""
+Get the list of upper bounds.
+"""
+function get_upper_bound_list end 
+
+"""
+Read bound value for c_idx.
+"""
+function get_bound end
+
+
+## Changing the bounds constraints.
+"""
+Change the value of the bound c_idx.
+"""
+function set_bound! end
+
+"""
+Delete bounds.
+"""
+function delete_bounds! end
+
+"""
+Add bound constraint.
+"""
+function add_bound_constraint! end
+
+
+## Checks 
+"""
+Check if the subject of the bound c_idx is an integer variable (recorded in int_vars).
+"""
+function is_constraint_on_int_var end
+
+"""
+To check if there is bound for the variable in the global or node bounds.
+"""
+function is_bound_in end
+
+"""
+Is a given point v linear feasible for the model?
+That means does v satisfy all bounds and other linear constraints?
+"""
+function is_linear_feasible end
+
+"""
+Has variable a binary constraint?
+"""
+function has_binary_constraint end
+
+"""
+Has variable an integer constraint?
+"""
+function has_integer_constraint end
+
+
+
+#################### Optional to implement ####################
+
+# These are safety check, utilities and log functions.
+# They are not strictly necessary for Boscia to run but would be beneficial to add, especially in the case of the safety functions.
+
+## Safety Functions
+"""
+Check if the bounds were set correctly in build_LMO.
+Safety check only.
+"""
+function build_LMO_correct(blmo::BoundedLinearMinimizationOracle, node_bounds)
+    return true
+end
+
+"""
+Check if problem is bounded and feasible, i.e. no contradicting constraints.
+"""
+function check_feasibility(blmo::BoundedLinearMinimizationOracle)
+    return MOI.OPTIMAL
+end
+
+"""
+Check whether a split is valid, i.e. the upper and lower on variable vidx are not the same. 
+"""
+function is_valid_split(tree::Bonobo.BnBTree, blmo::BoundedLinearMinimizationOracle, vidx::Int)
+    return true
+end
+
+"""
+Is a given point v indicator feasible, i.e. meets the indicator constraints? If applicable.
+"""
+function is_indicator_feasible(blmo::BoundedLinearMinimizationOracle, v; atol= 1e-6, rtol=1e-6)
+    return true
+end
+
+"""
+Are indicator constraints present?
+"""
+function indicator_present(blmo::BoundedLinearMinimizationOracle)
+    return false
+end
+
+"""
+Deal with infeasible vertex if necessary, e.g. check what caused it etc.
+"""
+function check_infeasible_vertex(blmo::BoundedLinearMinimizationOracle, tree)
+end
+
+
+## Utility
+"""
+Free model data from previous solve (if necessary).
+"""
+function free_model(blmo::BoundedLinearMinimizationOracle)
+    return true
+end
+
+"""
+Get solving tolerance for the BLMO.
+"""
+function get_tol(blmo::BoundedLinearMinimizationOracle)
+    return 1e-6
+end
+
+"""
+Find best solution from the solving process.
+"""
+function find_best_solution(f::Function, blmo::BoundedLinearMinimizationOracle, vars, domain_oracle)
+    return (nothing, Inf)
+end
+
+"""
+List of all variable pointers. Depends on how you save your variables internally. In the easy case, this is simply `collect(1:N)`.
+
+Is used in `find_best_solution`.
+"""
+function get_variables_pointers(blmo::BoundedLinearMinimizationOracle, tree)
+    N = tree.root.problem.nvars
+    return collect(1:N)
+end
+
+
+## Logs
+"""
+Get solve time, number of nodes and number of iterations, if applicable.
+"""
+function get_BLMO_solve_data(blmo::BoundedLinearMinimizationOracle)
+    return 0.0, 0.0, 0.0
+end